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Muraleedharan AK, Co K, Vallet M, Zaki A, Karolak F, Bogicevic C, Perronet K, Dkhil B, Paillard C, Fiorini-Debuisschert C, Treussart F. Ferroelectric Texture of Individual Barium Titanate Nanocrystals. ACS NANO 2024; 18:18355-18367. [PMID: 38952163 DOI: 10.1021/acsnano.4c02291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/03/2024]
Abstract
Ferroelectric materials display exotic polarization textures at the nanoscale that could be used to improve the energetic efficiency of electronic components. The vast majority of studies were conducted in two dimensions on thin films that can be further nanostructured, but very few studies address the situation of individual isolated nanocrystals (NCs) synthesized in solution, while such structures could have other fields of applications. In this work, we experimentally and theoretically studied the polarization texture of ferroelectric barium titanate (BaTiO3, BTO) NCs attached to a conductive substrate and surrounded by air. We synthesized NCs of well-defined quasicubic shape and 160 nm average size that conserve the tetragonal structure of BTO at room temperature. We then investigated the inverse piezoelectric properties of such pristine individual NCs by vector piezoresponse force microscopy (PFM), taking particular care to suppress electrostatic artifacts. In all of the NCs studied, we could not detect any vertical PFM signal, and the maps of the lateral response all displayed larger displacement amplitude on the edges with deformations converging toward the center. Using field phase simulations dedicated to ferroelectric nanostructures, we were able to predict the equilibrium polarization texture. These simulations revealed that the NC core is composed of 180° up and down domains defining the polar axis that rotate by 90° in the two facets orthogonal to this axis, eventually lying within these planes forming a layer of about 10 nm thickness mainly composed of 180° domains along an edge. From this polarization distribution, we predicted the lateral PFM response, which was revealed to be in very good qualitative agreement with the experimental observations. This work positions PFM as a relevant tool to evaluate the potential of complex ferroelectric nanostructures to be used as sensors.
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Affiliation(s)
- Athulya K Muraleedharan
- Université Paris-Saclay, ENS Paris-Saclay, CNRS, CentraleSupélec, LuMIn, 91190 Gif-sur-Yvette, France
| | - Kevin Co
- Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS, 91190 Gif-sur-Yvette, France
| | - Maxime Vallet
- Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS, 91190 Gif-sur-Yvette, France
| | - Abdelali Zaki
- Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS, 91190 Gif-sur-Yvette, France
| | - Fabienne Karolak
- Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS, 91190 Gif-sur-Yvette, France
| | - Christine Bogicevic
- Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS, 91190 Gif-sur-Yvette, France
| | - Karen Perronet
- Université Paris-Saclay, ENS Paris-Saclay, CNRS, CentraleSupélec, LuMIn, 91190 Gif-sur-Yvette, France
| | - Brahim Dkhil
- Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS, 91190 Gif-sur-Yvette, France
| | - Charles Paillard
- Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS, 91190 Gif-sur-Yvette, France
- Smart Ferroic Materials Center, Institute for Nanoscience & Engineering and Department of Physics, University of Arkansas, Fayetteville, 72701 Arkansas, United States
| | | | - François Treussart
- Université Paris-Saclay, ENS Paris-Saclay, CNRS, CentraleSupélec, LuMIn, 91190 Gif-sur-Yvette, France
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2
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Jeong C, Lee J, Jo H, Oh J, Baik H, Go KJ, Son J, Choi SY, Prosandeev S, Bellaiche L, Yang Y. Revealing the three-dimensional arrangement of polar topology in nanoparticles. Nat Commun 2024; 15:3887. [PMID: 38719801 PMCID: PMC11078976 DOI: 10.1038/s41467-024-48082-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 04/16/2024] [Indexed: 05/12/2024] Open
Abstract
In the early 2000s, low dimensional ferroelectric systems were predicted to have topologically nontrivial polar structures, such as vortices or skyrmions, depending on mechanical or electrical boundary conditions. A few variants of these structures have been experimentally observed in thin film model systems, where they are engineered by balancing electrostatic charge and elastic distortion energies. However, the measurement and classification of topological textures for general ferroelectric nanostructures have remained elusive, as it requires mapping the local polarization at the atomic scale in three dimensions. Here we unveil topological polar structures in ferroelectric BaTiO3 nanoparticles via atomic electron tomography, which enables us to reconstruct the full three-dimensional arrangement of cation atoms at an individual atom level. Our three-dimensional polarization maps reveal clear topological orderings, along with evidence of size-dependent topological transitions from a single vortex structure to multiple vortices, consistent with theoretical predictions. The discovery of the predicted topological polar ordering in nanoscale ferroelectrics, independent of epitaxial strain, widens the research perspective and offers potential for practical applications utilizing contact-free switchable toroidal moments.
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Affiliation(s)
- Chaehwa Jeong
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Juhyeok Lee
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Energy Geosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Hyesung Jo
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Jaewhan Oh
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Hionsuck Baik
- Korea Basic Science Institute (KBSI), Seoul, 02841, Republic of Korea
| | - Kyoung-June Go
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Junwoo Son
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Si-Young Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
- Center for Van der Waals Quantum Solids, Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea
| | - Sergey Prosandeev
- Smart Ferroic Materials Center (SFMC), Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Laurent Bellaiche
- Smart Ferroic Materials Center (SFMC), Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Yongsoo Yang
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
- Graduate School of Semiconductor Technology, School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
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3
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Lombardi J, Yang L, Farahmand N, Ruffino A, Younes A, Spanier JE, Billinge SJL, O'Brien S. Structure and phase transitions in niobium and tantalum derived nanoscale transition metal perovskites, Ba(Ti,MV)O3, M=Nb,Ta. J Chem Phys 2024; 160:134702. [PMID: 38573849 DOI: 10.1063/5.0192488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 02/19/2024] [Indexed: 04/06/2024] Open
Abstract
The prospect of creating ferroelectric or high permittivity nanomaterials provides motivation for investigating complex transition metal oxides of the form Ba(Ti, MV)O3, where M = Nb or Ta. Solid state processing typically produces mixtures of crystalline phases, rarely beyond minimally doped Nb/Ta. Using a modified sol-gel method, we prepared single phase nanocrystals of Ba(Ti, M)O3. Compositional and elemental analysis puts the empirical formulas close to BaTi0.5Nb0.5O3-δ and BaTi0.5Ta0.5O3-δ. For both materials, a reversible temperature dependent phase transition (non-centrosymmetric to symmetric) is observed in the Raman spectrum in the region 533-583 K (260-310 °C); for Ba(Ti, Nb)O3, the onset is at 543 K (270 °C); and for Ba(Ti, Ta)O3, the onset is at 533 K (260 °C), which are comparable with 390-393 K (117-120 °C) for bulk BaTiO3. The crystal structure was resolved by examination of the powder x-ray diffraction and atomic pair distribution function (PDF) analysis of synchrotron total scattering data. It was postulated whether the structure adopted at the nanoscale was single or double perovskite. Double perovskites (A2B'B″O6) are characterized by the type and extent of cation ordering, which gives rise to higher symmetry crystal structures. PDF analysis was used to examine all likely candidate structures and to look for evidence of higher symmetry. The feasible phase space that evolves includes the ordered double perovskite structure Ba2(Ti, MV)O6 (M = Nb, Ta) Fm-3m, a disordered cubic structure, as a suitable high temperature analog, Ba(Ti, MV)O3Pm-3m, and an orthorhombic Ba(Ti, MV)O3Amm2, a room temperature structure that presents an unusually high level of lattice displacement, possibly due to octahedral tilting, and indication of a highly polarized crystal.
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Affiliation(s)
- Julien Lombardi
- The CUNY Energy Institute, City University of New York, Steinman Hall, 160 Convent Avenue, The City College of New York, New York, New York 10031, USA
- Department of Chemistry and Biochemistry, The City College of New York, 1024 Marshak, 160 Convent Avenue, New York, New York 10031, USA
- Ph.D. Program in Chemistry, The Graduate Center, The City University of New York, New York, New York 10016, USA
| | - Long Yang
- School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804, China
| | - Nasim Farahmand
- The CUNY Energy Institute, City University of New York, Steinman Hall, 160 Convent Avenue, The City College of New York, New York, New York 10031, USA
- Department of Chemistry and Biochemistry, The City College of New York, 1024 Marshak, 160 Convent Avenue, New York, New York 10031, USA
- Ph.D. Program in Chemistry, The Graduate Center, The City University of New York, New York, New York 10016, USA
| | - Anthony Ruffino
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - Ali Younes
- Department of Chemistry, Hunter College of the City University of New York, 695 Park Ave., New York, New York 10065, USA
| | - Jonathan E Spanier
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, USA
- Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - Simon J L Billinge
- Department of Applied Physics and Applied Mathematics, Columbia University, 500 West 120th Street, New York, New York 10027, USA
| | - Stephen O'Brien
- The CUNY Energy Institute, City University of New York, Steinman Hall, 160 Convent Avenue, The City College of New York, New York, New York 10031, USA
- Department of Chemistry and Biochemistry, The City College of New York, 1024 Marshak, 160 Convent Avenue, New York, New York 10031, USA
- Ph.D. Program in Chemistry, The Graduate Center, The City University of New York, New York, New York 10016, USA
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4
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Minami S, Ikeda Y, Shimada T. Spontaneous Atomic-Scale Polar Skyrmions and Merons on a SrTiO 3 (001) Surface: Defect Engineering for Emerging Topological Orders. NANO LETTERS 2024; 24:3686-3693. [PMID: 38451549 DOI: 10.1021/acs.nanolett.3c05112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
The emergence of nontrivial topological order in condensed matter has been attracting a great deal of attention owing to its promising technological applications in novel functional nanodevices. In ferroelectrics, the realization of polar topological order at an ultimately small scale is extremely challenging due to the lack of chiral interaction and the critical size of the ferroelectricity. Here, we break through these limitations and demonstrate that the ultimate atomic-scale polar skyrmion and meron (∼2 nm) can be induced by engineering oxygen vacancies on the SrTiO3 (001) surface based on first-principles calculations. The paraelectric-to-antiferrodistortive phase transition leads to a novel topological transition from skyrmion to meron, indicating phase-topology correlations. We also discuss accumulating and driving polar skyrmions based on the oxygen divacancy model; these results and the recent discovery of defect engineering techniques suggest the possibility of arithmetic operations on topological numbers through the natural self-organization and diffusion features of oxygen vacancies.
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Affiliation(s)
- Susumu Minami
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Yoshitaka Ikeda
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Takahiro Shimada
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
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5
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Xu T, Mori M, Hirakata H, Kitamura T, Shimada T. Emergent ultrasmall multiferroics in paraelectric perovskite oxide by hole polarons. Phys Chem Chem Phys 2024; 26:842-847. [PMID: 38108227 DOI: 10.1039/d3cp05364d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Ultimately small multiferroics with coupled ferroelectric and ferromagnetic order parameters have drawn considerable attention for their tremendous technological potential. Nevertheless, these ferroic orders inevitably disappear below the critical size of several nanometers in conventional ferroelectrics or multiferroics. Here, based on first-principles calculations, we propose a new strategy to overcome this limitation and create ultrasmall multiferroic elements in otherwise nonferroelectric CaTiO3 by engineering the interplay of oxygen octahedral rotations and hole polarons, though both of them are generally believed to be detrimental to ferroelectricity. It is found that the hole doped in CaTiO3 spontaneously forms a localized polaronic state. The lattice distortions associated with a hole polaron interacting with the intrinsic oxygen octahedral rotations in CaTiO3 effectively break the inversion symmetry and create atomic-scale ferroelectricity beyond the critical size limitation. The hole polaron also causes highly localized magnetism attributed to the associated spin-polarized electric state and thus manifests as a multiferroic polaron. Moreover, the hole polaron exhibits high hopping mobility accompanied by rich switching of polarization and magnetic directions, indicating strong magnetoelectric coupling with a mechanism dissimilar from that of conventional multiferroics. The present work provides a new mechanism to engineer inversion symmetry and opens avenues for designing unusual multifunctional materials.
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Affiliation(s)
- Tao Xu
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan.
| | - Masataka Mori
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan.
| | - Hiroyuki Hirakata
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan.
| | - Takayuki Kitamura
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan.
| | - Takahiro Shimada
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan.
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6
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Cecchi S, Momand J, Dragoni D, Abou El Kheir O, Fagiani F, Kriegner D, Rinaldi C, Arciprete F, Holý V, Kooi BJ, Bernasconi M, Calarco R. Thick Does the Trick: Genesis of Ferroelectricity in 2D GeTe-Rich (GeTe) m (Sb 2 Te 3 ) n Lamellae. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2304785. [PMID: 37988708 PMCID: PMC10767439 DOI: 10.1002/advs.202304785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/28/2023] [Indexed: 11/23/2023]
Abstract
The possibility to engineer (GeTe)m (Sb2 Te3 )n phase-change materials to co-host ferroelectricity is extremely attractive. The combination of these functionalities holds great technological impact, potentially enabling the design of novel multifunctional devices. Here an experimental and theoretical study of epitaxial (GeTe)m (Sb2 Te3 )n with GeTe-rich composition is presented. These layered films feature a tunable distribution of (GeTe)m (Sb2 Te3 )1 blocks of different sizes. Breakthrough evidence of ferroelectric displacement in thick (GeTe)m (Sb2 Te3 )1 lamellae is provided. The density functional theory calculations suggest the formation of a tilted (GeTe)m slab sandwiched in GeTe-rich blocks. That is, the net ferroelectric polarization is confined almost in-plane, representing an unprecedented case between 2D and bulk ferroelectric materials. The ferroelectric behavior is confirmed by piezoresponse force microscopy and electroresistive measurements. The resilience of the quasi van der Waals character of the films, regardless of their composition, is also demonstrated. Hence, the material developed hereby gathers in a unique 2D platform the phase-change and ferroelectric switching properties, paving the way for the conception of innovative device architectures.
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Affiliation(s)
- Stefano Cecchi
- Department of Materials ScienceUniversity of Milano‐Bicoccavia R. Cozzi 5520125MilanoItaly
- Paul‐Drude‐Institut für FestkörperelektronikLeibniz‐Institut im Forschungsverbund Berlin e.V.Hausvogteiplatz 5‐710117BerlinGermany
| | - Jamo Momand
- Zernike Institute for Advanced MaterialsUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Daniele Dragoni
- Department of Materials ScienceUniversity of Milano‐Bicoccavia R. Cozzi 5520125MilanoItaly
| | - Omar Abou El Kheir
- Department of Materials ScienceUniversity of Milano‐Bicoccavia R. Cozzi 5520125MilanoItaly
| | - Federico Fagiani
- Dipartimento di FisicaPolitecnico di MilanoP.zza Leonardo da Vinci 3220133MilanoItaly
| | - Dominik Kriegner
- Institute of Solid State and Materials PhysicsTechnische Universität DresdenHelmholtzstr. 1001069DresdenGermany
- Institute of PhysicsCzech Academy of SciencesCukrovarnická 10/11216200Praha 6Czech Republic
| | - Christian Rinaldi
- Dipartimento di FisicaPolitecnico di MilanoP.zza Leonardo da Vinci 3220133MilanoItaly
| | - Fabrizio Arciprete
- Dipartimento di FisicaUniversità di Roma “Tor Vergata”Via della Ricerca Scientifica 100133RomeItaly
| | - Vaclav Holý
- Department of Condensed Matter PhysicsFaculty of Mathematics and PhysicsCharles University, Ke Karlovu 512116PrahaCzech Republic
- Institute of Condensed Matter PhysicsFaculty of ScienceMasaryk UniversityKotlářská 2611 37BrnoCzech Republic
| | - Bart J. Kooi
- Zernike Institute for Advanced MaterialsUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Marco Bernasconi
- Department of Materials ScienceUniversity of Milano‐Bicoccavia R. Cozzi 5520125MilanoItaly
| | - Raffaella Calarco
- Paul‐Drude‐Institut für FestkörperelektronikLeibniz‐Institut im Forschungsverbund Berlin e.V.Hausvogteiplatz 5‐710117BerlinGermany
- CNR Institute for Microelectronics and Microsystems–IMMConsiglio Nazionale delle RicercheVia del Fosso del Cavaliere 10000133RomaItaly
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Xu T, Zhang J, Shimada T, Wang J, Yang H. Intrinsic Atomic-Scale Antiferroelectric VOF 3 Nanowire with Ultrahigh-Energy Storage Properties. NANO LETTERS 2023; 23:9080-9086. [PMID: 37722001 DOI: 10.1021/acs.nanolett.3c02929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/20/2023]
Abstract
Antiferroelectrics with antiparallel dipoles are receiving tremendous attention for their technological importance and fundamental interest. However, intrinsic one-dimensional (1D) materials harboring antiferroelectric ordering have rarely been reported despite the promise of novel paradigms for miniaturized and high-density electronics. Herein, based on first- and second-principles calculations, we demonstrate the VOF3 atomic wire, exfoliated from an experimentally synthesized yet underexplored 1D van der Waals (vdW) bulk, as a new 1D antiferroelectric material. The energetic, thermal, and dynamic stabilities of the nanowire are confirmed theoretically. Moreover, the temperature-dependent phase transitions and double-hysteresis polarization-field loops are computed for the VOF3 nanowire by constructing the second-principles model. According to the hysteresis loops, high energy densities and efficiencies can be obtained simultaneously at room temperature in the VOF3 nanowire under moderate applied fields. Our identified 1D atomic wire not only expands the family of antiferroelectricity but also holds potential for novel high-power energy storage nanodevices.
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Affiliation(s)
- Tao Xu
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Jingtong Zhang
- Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, China
- Zhejiang Laboratory, Hangzhou, Zhejiang 311100, China
| | - Takahiro Shimada
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Jie Wang
- Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, China
- Zhejiang Laboratory, Hangzhou, Zhejiang 311100, China
| | - Hongxin Yang
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
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8
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Zhang T, Qi N, Su X, Tang X, Chen Z. Vacancy Suppression Induced Synergetic Optimization of Thermoelectric Performance in Sb-Doped GeTe Evidenced by Positron Annihilation Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2023; 15:40665-40675. [PMID: 37585556 DOI: 10.1021/acsami.3c08779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
Synergetic optimization of the electrical and thermal transport performance of GeTe has been achieved through Sb doping in this work, resulting in a high thermoelectric figure of merit ZT of 2.2 at 723 K. Positron annihilation measurements provided clear evidence that Sb doping in GeTe can effectively suppress the Ge vacancies, and the decrease of vacancy concentration coincides well with the change of hole carrier concentration after Sb doping. The decreased scattering by hole carriers and vacancies causes notable increase in carrier mobility. Despite this, the density of states effective mass is not enhanced by Sb doping, a maximum power factor of 4562 μW m-1 K-2 at 723 K is obtained for Ge0.94Sb0.06Te with an optimized carrier concentration of ∼3.65 × 1020 cm-3. Meanwhile, the electronic thermal conductivity κe is reduced because of the decreased electrical conductivity σ with the increase of the Sb doping amount. In addition, the lattice thermal conductivity κL is also suppressed due to multiple phonon scattering mechanism, such as the large mass and strain fluctuations by the substitution of Sb for Ge atoms, and also the unique microstructure including grain boundary, nano-pore, and dislocation in the samples. In conclusion, a maximum ZT of 2.2 is gained at 723 K, which contributes to preferable TE property for GeTe-based materials.
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Affiliation(s)
- Tingdong Zhang
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Ning Qi
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Xianli Su
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Xinfeng Tang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Zhiquan Chen
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
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9
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Yang S, Sui F, Liu Y, Qi R, Feng X, Dong S, Yang P, Yue F. Anisotropy and thermal properties in GeTe semiconductor by Raman analysis. NANOSCALE 2023; 15:13297-13303. [PMID: 37539838 DOI: 10.1039/d3nr02678g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
Low-symmetric GeTe semiconductors have attracted wide-ranging attention due to their excellent optical and thermal properties, but only a few research studies are available on their in-plane optical anisotropic nature that is crucial for their applications in optoelectronic and thermoelectric devices. Here, we investigate the optical interactions of anisotropy in GeTe using polarization-resolved Raman spectroscopy and first-principles calculations. After determining both armchair and zigzag directions in GeTe crystals by transmission electron microscopy, we found that the Raman intensity of the two main vibrational modes had a strong in-plane anisotropic nature; the one at ∼88.1 cm-1 can be used to determine the crystal orientation, and the other at ∼124.6 cm-1 can reveal a series of temperature-dependent phase transitions. These results provide a general approach for the investigation of the anisotropy of light-matter interactions in low-symmetric layered materials, benefiting the design and application of optoelectronic, anisotropic thermoelectric, and phase-transition memory devices based on bulk GeTe.
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Affiliation(s)
- Shuai Yang
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
| | - Fengrui Sui
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
| | - Yucheng Liu
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
| | - Ruijuan Qi
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
| | - Xiaoyu Feng
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
| | - Shangwei Dong
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
| | - Pingxiong Yang
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
| | - Fangyu Yue
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
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10
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Yasui K. Critical Roles of Impurities and Imperfections in Various Phases of Materials. MATERIALS (BASEL, SWITZERLAND) 2023; 16:ma16041612. [PMID: 36837241 PMCID: PMC9960772 DOI: 10.3390/ma16041612] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/08/2023] [Accepted: 02/13/2023] [Indexed: 06/01/2023]
Abstract
In many materials, impurities and imperfections play a critical role on the physical and chemical properties. In the present review, some examples of such materials are discussed. A bulk nanobubble (an ultrafine bubble) is stabilized against dissolution by hydrophobic impurities attached to the bubble surface. An acoustic cavitation threshold in various liquids decreases significantly by the presence of impurities such as solid particles, etc. The strength of brittle ceramics is determined by the size and number of pre-existing microcracks (imperfections) in the specimen. The size effect of a BaTiO3 nanocrystal is influenced by the amount and species of adsorbates (impurities) on its surface as adsorbate-induced charge-screening changes the free energy. The dielectric constant of an assembly of BaTiO3 nanocubes is influenced by a small tilt angle (imperfection) between two attached nanocubes, which induces strain inside a nanocube, and is also influenced by the spatial strain-relaxation due to defects and dislocations (imperfections), resulting in flexoelectric polarization.
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Affiliation(s)
- Kyuichi Yasui
- National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560, Japan
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11
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A Ferroelectric Memristor-Based Transient Chaotic Neural Network for Solving Combinatorial Optimization Problems. Symmetry (Basel) 2022. [DOI: 10.3390/sym15010059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A transient chaotic neural network (TCNN) is particularly useful for solving combinatorial optimization problems, and its hardware implementation based on memristors has attracted great attention recently. Although previously used filamentary memristors could provide the desired nonlinearity for implementing the annealing function of a TCNN, the controllability of filamentary switching still remains relatively poor, thus limiting the performance of a memristor-based TCNN. Here, we propose to use ferroelectric memristor to implement the annealing function of a TCNN. In the ferroelectric memristor, the conductance can be tuned by switching the lattice non-centrosymmetry-induced polarization, which is a nonlinear switching mechanism with high controllability. We first establish a ferroelectric memristor model based on a ferroelectric tunnel junction (FTJ), which exhibits the polarization-modulated tunnel conductance and the nucleation-limited-switching (NLS) behavior. Then, the conductance of the ferroelectric memristor is used as the self-feedback connection weight that can be dynamically adjusted. Based on this, a ferroelectric memristor-based transient chaotic neural network (FM-TCNN) is further constructed and applied to solve the traveling salesman problem (TSP). In 1000 runs for 10-city TSP, the FM-TCNN achieves a shorter average path distance, a 32.8% faster convergence speed, and a 2.44% higher global optimal rate than the TCNN.
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12
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Li Q, Sun J, Zhang Y, Li T, Liu H, Cao Y, Zhang Q, Gu L, Honda T, Ikeda K, Otomo T, Lin K, Deng J, Xing X. Ferroelectric Ordering in Nanosized PbTiO 3. NANO LETTERS 2022; 22:9405-9410. [PMID: 36410727 DOI: 10.1021/acs.nanolett.2c03303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The insight into the three-dimensional configuration of ferroelectric ordering in ferroelectric nanomaterials is motivated by the application of the development of functional nanodevices and the structural designing. However, the atomic deciphering of the spatial distribution of ordered structure remains challenging for the limitation of dimension and probing techniques. In this paper, a neutron pair distribution function (nPDF) was utilized to analyze the spontaneous polarization distribution of zero-dimensional PbTiO3 nanoparticles in three dimensions, via the application of reverse Monte Carlo (RMC) modeling. The comprehensive identification with transmission electron microscopy verified the linear characteristics of polarization along the c-axis in the main body, while electric polarization distribution on the surface was enhanced abnormally. In addition, the correlation of dipole vectors extending to three unit cells below the surface is retained. This work shows an application of the micro/macroscale information to effectively decode the polarization structure of nanoferroelectrics, providing new views of designing nanoferroelectric devices.
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Affiliation(s)
- Qiang Li
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Jing Sun
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Yuanpeng Zhang
- Neutron Science Division, Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, United States
| | - Tianyu Li
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Hui Liu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Yili Cao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Science, Beijing 100190, China
| | - Lin Gu
- Beijing National Center for Electron Microscopy and Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Takashi Honda
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - Kazutaka Ikeda
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - Toshiya Otomo
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - Kun Lin
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Jinxia Deng
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Xianran Xing
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
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13
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Dantelle G, Beauquis S, Le Dantec R, Monnier V, Galez C, Mugnier Y. Solution-Based Synthesis Routes for the Preparation of Noncentrosymmetric 0-D Oxide Nanocrystals with Perovskite and Nonperovskite Structures. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200992. [PMID: 35691941 DOI: 10.1002/smll.202200992] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/21/2022] [Indexed: 06/15/2023]
Abstract
With the miniaturization of electronic-based devices, the foreseen potential of new optical nanoprobes and the assessment of eventual size and shape effects, elaboration of multifunctional noncentrosymmetric nanocrystals with ferroelectric, pyroelectric, piezoelectric, and nonlinear optical properties are the subject of an increasing research interest. Here, the recent achievements from the solution-based methods (coprecipitation in homogeneous and nanostructured media, sol-gel processes including various chemistries and hydro/solvothermal techniques) to prepare 0-D perovskite and nonperovskite oxides in the 5-500 nm size range are critically reviewed. To cover a representative list of covalent- and ionic-type materials, BaTiO3 and its derivatives, niobate compounds (i.e., K/Na/LiNbO3 ), multiferroic BiFeO3, and crystals of lower symmetry including KTiOPO4 and some iodate compounds such as Fe(IO3 )3 and La(IO3 )3 are systematically in focus. The resulting size, morphology, and aggregation state are discussed in light of the proposed formation mechanisms. Because of a higher complexity related to their chemical composition and crystalline structures, improving the rational design of these multifunctional oxides in terms of finely-tuned compositions, crystalline hosts and structure-property relationships still need in the future a special attention of the research community to the detailed understanding of the reaction pathways and crystallization mechanisms.
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Affiliation(s)
- Géraldine Dantelle
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble, 38000, France
| | | | - Ronan Le Dantec
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
| | - Virginie Monnier
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, Ecully, 69130, France
| | - Christine Galez
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
| | - Yannick Mugnier
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
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14
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Leonardi A, Neder R, Engel M. Efficient solution of particle shape functions for the analysis of powder total scattering data. J Appl Crystallogr 2022; 55:329-339. [PMID: 35497652 PMCID: PMC8985607 DOI: 10.1107/s1600576722001261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 02/02/2022] [Indexed: 11/10/2022] Open
Abstract
Structural characterization of powder samples via total scattering methods, in either real or reciprocal space, must take into account the effect of particle shape. Here, the shape contribution of a set of ideally isolated particles to the small-angle scattering (SAS) component of the intensity profile is modelled using the shape function [Svergun & Koch (2003). Rep. Prog. Phys. 66, 1735-1782]. The shape function is obtained by orientational averaging of common volume functions (CVFs) for a discrete set of directions. The effects of particle size and size dispersity are accounted for via scaling of the CVFs and their convolution with the underlying probability distribution. The method is applied to shapes with CVFs expressed analytically or by using discrete tables. The accurate calculation of SAS particle shape contributions up to large momentum transfer demonstrates the reliability and flexibility of modelling shape functions from sets of CVFs. The algorithm presented here is computationally efficient and can be directly incorporated into existing routines for analysis of powder total scattering data.
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Affiliation(s)
- Alberto Leonardi
- Institute for Multiscale Simulation, IZNF, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstrasse 3, Erlangen, Bavaria 91058, Germany
| | - Reinhard Neder
- Institut für Physik der Kondensierten Materie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudstrasse 3, Erlangen, Bavaria 91058, Germany
| | - Michael Engel
- Institute for Multiscale Simulation, IZNF, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstrasse 3, Erlangen, Bavaria 91058, Germany
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15
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Augurio A, Alvarez-Fernandez A, Panchal V, Pittenger B, De Wolf P, Guldin S, Briscoe J. Controlled Porosity in Ferroelectric BaTiO 3 Photoanodes. ACS APPLIED MATERIALS & INTERFACES 2022; 14:13147-13157. [PMID: 35271773 PMCID: PMC8949718 DOI: 10.1021/acsami.1c17419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 01/14/2022] [Indexed: 05/17/2023]
Abstract
The use of ferroelectric polarization to promote electron-hole separation has emerged as a promising strategy to improve photocatalytic activity. Although ferroelectric thin films with planar geometry have been largely studied, nanostructured and porous ferroelectric thin films have not been commonly used in photo-electrocatalysis. The inclusion of porosity in ferroelectric thin films would enhance the surface area and reactivity, leading to a potential improvement of the photoelectrochemical (PEC) performance. Herein, the preparation of porous barium titanate (pBTO) thin films by a soft template-assisted sol-gel method is reported, and the control of porosity using different organic/inorganic ratios is verified by the combination of scanning electron microscopy and ellipsometry techniques. Using piezoresponse force microscopy, the switching of ferroelectric domains in pBTO thin films is observed, confirming that the ferroelectric polarization is still retained in the porous structures. In addition, the presence of porosity in pBTO thin films leads to a clear improvement of the PEC response. By electrochemical poling, we also demonstrated the tuning of the PEC performance of pBTO thin films via ferroelectric polarization. Our work offers a simple and low-cost approach to control the morphology optimization of ferroelectric thin films, which could open up the development of materials with great potential for PEC applications.
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Affiliation(s)
- Adriana Augurio
- School
of Engineering and Material Science and Materials Research Institute, Queen Mary University of London, E1 4NS London, U.K.
| | - Alberto Alvarez-Fernandez
- Department
of Chemical Engineering, University College
London, Torrington Place, WC1E 7JE London, U.K.
| | | | - Bede Pittenger
- AFM
Unit, Bruker Nano Surfaces, 93117 Santa Barbara, California, United States
| | - Peter De Wolf
- AFM
Unit, Bruker Nano Surfaces, 93117 Santa Barbara, California, United States
| | - Stefan Guldin
- Department
of Chemical Engineering, University College
London, Torrington Place, WC1E 7JE London, U.K.
| | - Joe Briscoe
- School
of Engineering and Material Science and Materials Research Institute, Queen Mary University of London, E1 4NS London, U.K.
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16
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Cottingham P, Brutchey RL. Temperature-dependent behavior in the local structure of BaTiO 3 nanocrystals. CrystEngComm 2022. [DOI: 10.1039/d2ce00705c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We use pair distribution function analysis of synchrotron X-ray total scattering data to inspect the local structure of BaTiO3 nanocrystals from 253 K < T < 413 K.
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Affiliation(s)
- Patrick Cottingham
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
| | - Richard L. Brutchey
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
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17
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Zhang G, Li Q, Allahyarov E, Li Y, Zhu L. Challenges and Opportunities of Polymer Nanodielectrics for Capacitive Energy Storage. ACS APPLIED MATERIALS & INTERFACES 2021; 13:37939-37960. [PMID: 34370438 DOI: 10.1021/acsami.1c04991] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
With the modern development of power electrification, polymer nanocomposite dielectrics (or nanodielectrics) have attracted significant research attention. The idea is to combine the high dielectric constant of inorganic nanofillers and the high breakdown strength/low loss of a polymer matrix for higher energy density polymer film capacitors. Although impressively high energy density has been achieved at the laboratory scale, there is still a large gap from the eventual goal of polymer nanodielectric capacitors. In this review, we focus on essential material issues for two types of polymer nanodielectrics, polymer/conductive nanoparticle and polymer/ceramic nanoparticle composites. Various material design parameters, including dielectric constant, dielectric loss, breakdown strength, high temperature rating, and discharged energy density will be discussed from both fundamental science and high-voltage capacitor application points of view. The objective is to identify advantages and disadvantages of the polymer nanodielectric approach against other approaches utilizing neat dielectric polymers and ceramics. Given the state-of-the-art understanding, future research directions are outlined for the continued development of polymer nanodielectrics for electric energy storage applications.
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Affiliation(s)
- Guoqiang Zhang
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7202, United States
| | - Qiong Li
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7202, United States
| | - Elshad Allahyarov
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7202, United States
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
- Theoretical Department, Joint Institute for High Temperatures, Russian Academy of Sciences, 13/19 Izhorskaya Street, Moscow 125412, Russia
| | - Yue Li
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
| | - Lei Zhu
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7202, United States
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18
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Su R, Wang Z, Zhu L, Pan Y, Zhang D, Wen H, Luo ZD, Li L, Li FT, Wu M, He L, Sharma P, Seidel J. Strain-Engineered Nano-Ferroelectrics for High-Efficiency Piezocatalytic Overall Water Splitting. Angew Chem Int Ed Engl 2021; 60:16019-16026. [PMID: 33871146 DOI: 10.1002/anie.202103112] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/12/2021] [Indexed: 12/22/2022]
Abstract
Developing nano-ferroelectric materials with excellent piezoelectric performance for piezocatalysts used in water splitting is highly desired but also challenging, especially with respect to reaching large piezo-potentials that fully align with required redox levels. Herein, heteroepitaxial strain in BaTiO3 nanoparticles with a designed porous structure is successfully induced by engineering their surface reconstruction to dramatically enhance their piezoelectricity. The strain coherence can be maintained throughout the nanoparticle bulk, resulting in a significant increase of the BaTiO3 tetragonality and thus its piezoelectricity. Benefiting from high piezoelectricity, the as-synthesized blue-colored BaTiO3 nanoparticles possess a superb overall water-splitting activity, with H2 production rates of 159 μmol g-1 h-1 , which is almost 130 times higher than that of the pristine BaTiO3 nanoparticles. Thus, this work provides a generic approach for designing highly efficient piezoelectric nanomaterials by strain engineering that can be further extended to various other perovskite oxides, including SrTiO3 , thereby enhancing their potential for piezoelectric catalysis.
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Affiliation(s)
- Ran Su
- College of Science, Hebei University of Science and Technology, Shijiazhuang, 050018, China
| | - Zhipeng Wang
- Frontier Institute of Science and Technology, State Key Laboratory for Mechanical behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Lina Zhu
- College of Science, Hebei University of Science and Technology, Shijiazhuang, 050018, China
| | - Ying Pan
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South, Wales, 2052, Australia
| | - Dawei Zhang
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South, Wales, 2052, Australia
| | - Hui Wen
- College of Electrical Engineering, Hebei University of Science and Technology, Shijiazhuang, 050018, China
| | - Zheng-Dong Luo
- Interuniversity Microelectronics Centre, Kapeldreef 75, 3001, Leuven, Belgium
| | - Linglong Li
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Fa-Tang Li
- College of Science, Hebei University of Science and Technology, Shijiazhuang, 050018, China
| | - Ming Wu
- Frontier Institute of Science and Technology, State Key Laboratory for Mechanical behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Liqiang He
- Frontier Institute of Science and Technology, State Key Laboratory for Mechanical behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Pankaj Sharma
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South, Wales, 2052, Australia
| | - Jan Seidel
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South, Wales, 2052, Australia
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19
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Farahmand N, McGinn CK, Zhang Q, Gai Z, Kymissis I, O'Brien S. Magnetic and dielectric property control in the multivalent nanoscale perovskite Eu 0.5Ba 0.5TiO 3. NANOSCALE 2021; 13:10365-10384. [PMID: 33988208 DOI: 10.1039/d1nr00588j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report nanoscale Eu0.5Ba0.5TiO3, a multiferroic in the bulk and candidate in the search to quantify the electric dipole moment of the electron. Eu0.5Ba0.5TiO3, in the form of nanoparticles and other nanostructures is interesting for nanocomposite integration, biomedical imaging and fundamental research, based upon the prospect of polarizability, f-orbital magnetism and tunable optical/radio luminescence. We developed a [non-hydrolytic]sol-[H2O-activated]gel route, derived from in-house metallic Ba(s)/Eu(s) alkoxide precursors and Ti{(OCH(CH3)2}4. Two distinct nanoscale compounds of Ba:Ti:Eu with the parent perovskite crystal structure were produced, with variable dielectric, magnetic and optical properties, based on altering the oxidizing/reducing conditions. Eu0.5Ba0.5TiO3 prepared under air/O2 atmospheres produced a spherical core-shell nanostructure (30-35 nm), with perovskite Eu0.5Ba0.5TiO3 nanocrystal core-insulating oxide shell layer (∼3 nm), presumed a pre-pyrochlore layer abundant with Eu3+. Fluorescence spectroscopy shows a high intensity 5D0→7F2 transition at 622 nm and strong red fluorescence. The core/shell structure demonstrated excellent capacitive properties: assembly into dielectric thin films gave low conductivity (2133 GΩ mm-1) and an extremely stable, low loss permittivity of εeff∼25 over a wide frequency range (tan δ < 0.01, 100 kHz-2 MHz). Eu0.5Ba0.5TiO3 prepared under H2/argon produced more irregular shaped nanocrystals (20-25) nm, with a thin film permittivity around 4 times greater (εeff 101, tan δ < 0.05, 10 kHz-2 MHz, σ∼59.54 kΩ mm-1). Field-cooled magnetization values of 0.025 emu g-1 for EBTO-Air and 0.84 emu g-1 for EBTO-Argon were observed. X-ray photoelectron spectroscopy analysis reveals a complex interplay of EuII/III/TiIII/IV configurations which contribute to the observed ferroic and fluorescence behavior.
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Affiliation(s)
- Nasim Farahmand
- The CUNY Energy Institute, City University of New York, Steinman Hall, 160 Convent Avenue, The City College of New York, New York, NY 10031, USA.
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20
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Superelastic oxide micropillars enabled by surface tension-modulated 90° domain switching with excellent fatigue resistance. Proc Natl Acad Sci U S A 2021; 118:2025255118. [PMID: 34117121 DOI: 10.1073/pnas.2025255118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Superelastic materials capable of recovering large nonlinear strains are ideal for a variety of applications in morphing structures, reconfigurable systems, and robots. However, making oxide materials superelastic has been a long-standing challenge due to their intrinsic brittleness. Here, we fabricate ferroelectric BaTiO3 (BTO) micropillars that not only are superelastic but also possess excellent fatigue resistance, lasting over 1 million cycles without accumulating residual strains or noticeable variation in stress-strain curves. Phase field simulations reveal that the large recoverable strains of BTO micropillars arise from surface tension-modulated 90° domain switching and thus are size dependent, while the small energy barrier and ultralow energy dissipation are responsible for their unprecedented cyclic stability among superelastic materials. This work demonstrates a general strategy to realize superelastic and fatigue-resistant domain switching in ferroelectric oxides for many potential applications.
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21
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Su R, Wang Z, Zhu L, Pan Y, Zhang D, Wen H, Luo Z, Li L, Li F, Wu M, He L, Sharma P, Seidel J. Strain‐Engineered Nano‐Ferroelectrics for High‐Efficiency Piezocatalytic Overall Water Splitting. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202103112] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Ran Su
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Zhipeng Wang
- Frontier Institute of Science and Technology State Key Laboratory for Mechanical behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
| | - Lina Zhu
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Ying Pan
- School of Materials Science and Engineering University of New South Wales Sydney, New South Wales 2052 Australia
| | - Dawei Zhang
- School of Materials Science and Engineering University of New South Wales Sydney, New South Wales 2052 Australia
| | - Hui Wen
- College of Electrical Engineering Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Zheng‐Dong Luo
- Interuniversity Microelectronics Centre Kapeldreef 75 3001 Leuven Belgium
| | - Linglong Li
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics Tsinghua University Beijing 100084 China
| | - Fa‐tang Li
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Ming Wu
- Frontier Institute of Science and Technology State Key Laboratory for Mechanical behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
| | - Liqiang He
- Frontier Institute of Science and Technology State Key Laboratory for Mechanical behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
| | - Pankaj Sharma
- School of Materials Science and Engineering University of New South Wales Sydney, New South Wales 2052 Australia
| | - Jan Seidel
- School of Materials Science and Engineering University of New South Wales Sydney, New South Wales 2052 Australia
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22
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Jiang B, Usher TM, Jothi PR, Kavey B, Caruntu G, Page K. Effect of Ligand Polarity on the Internal Dipoles and Ferroelectric Distortion in BaTiO 3 Nanocubes. Chemistry 2021; 27:8365-8371. [PMID: 33818851 DOI: 10.1002/chem.202100692] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Indexed: 11/08/2022]
Abstract
Surface adsorbates and surrounding matrix species have been demonstrated to affect the properties of nanoscale ferroelectrics and nanoscale ferroelectric composites; potentially counteracting performance losses that can occur in small particle sizes. In this work, the effects of nonpolar oleic acid (OA) and polar tetrafluoroborate (BF4 - ) ligand capping on the surface of various sizes of BaTiO3 nanocubes have been investigated with combined neutron diffraction and neutron pair distribution function (PDF), density functional theory (DFT), and ab initio molecular dynamics (AIMD) methods. The low real space PDF region provides an unobstructed view of rhombohedral (split short and long) Ti-O distances in BaTiO3 nanocubes, mimicking the well-established order-disorder local structure found in bulk BaTiO3 . Interestingly, the intermediate-range order in nanocubes is found to be orthorhombic, rather than tetragonal. It is concluded that polar ligands adsorbed at BaTiO3 surfaces stabilize the correlation length scale of local rhombohedral distortions in ferroelectric nanoparticles relative to nonpolar ligands.
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Affiliation(s)
- Bo Jiang
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Tedi-Marie Usher
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Palani Raja Jothi
- Materials Science and Engineering Department and Joint Institute for Advanced Materials, University of Tennessee, Knoxville, TN 37996, USA
| | - Benard Kavey
- Department of Chemistry and Biochemistry, Central Michigan University, 1200 S. Franklin St., Mount Pleasant, MI 48859, USA.,Science of Advanced Materials Program, Central Michigan University, 1200 S. Franklin St., Mount Pleasant, MI 48859, USA
| | - Gabriel Caruntu
- Department of Chemistry and Biochemistry, Central Michigan University, 1200 S. Franklin St., Mount Pleasant, MI 48859, USA.,Science of Advanced Materials Program, Central Michigan University, 1200 S. Franklin St., Mount Pleasant, MI 48859, USA
| | - Katharine Page
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.,Materials Science and Engineering Department and Joint Institute for Advanced Materials, University of Tennessee, Knoxville, TN 37996, USA
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23
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Accuracy and precision of position determination in ISTEM imaging of BaTiO 3. Ultramicroscopy 2021; 227:113325. [PMID: 34045084 DOI: 10.1016/j.ultramic.2021.113325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/07/2021] [Accepted: 05/18/2021] [Indexed: 11/21/2022]
Abstract
In this paper we study the effect of lens aberrations (spherical aberration and astigmatism), beam tilt, contamination and shot noise on the accuracy and precision of position determination in imaging scanning transmission electron microscopy (ISTEM) on the example of BaTiO3. ISTEM images are simulated as a function of sample thickness and defocus starting from a nearly perfect microscope setting. A defocus range was identified, in which atom column positions were reliably visible and could be decently measured. By averaging over this defocus and thickness range a figure of merit was defined and used to study the influence of above mentioned disturbing effects as a function of their strength. It turned out that column positions might become inaccurate, but distances are measured accurately. These were used to obtain recommendations for the experimental setup to measure the atomic arrangement that induces ferroelectric switching of BaTiO3.
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24
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Pasuk I, Neațu F, Neațu Ș, Florea M, Istrate CM, Pintilie I, Pintilie L. Structural Details of BaTiO 3 Nano-Powders Deduced from the Anisotropic XRD Peak Broadening. NANOMATERIALS 2021; 11:nano11051121. [PMID: 33925991 PMCID: PMC8147028 DOI: 10.3390/nano11051121] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/16/2021] [Accepted: 04/22/2021] [Indexed: 11/24/2022]
Abstract
In this study, nano-BaTiO3 (BTO) powders were obtained via the solvothermal method at different reaction times and were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The results were compared with those obtained for a larger crystallite size BTO powder (BTO-m). The sizes of the cuboid crystallites (as determined by XRD and TEM) ranged from about 18 to 24 nm, depending on the reaction time. The evolution with temperature of the structure parameters of nano-BTO was monitored by means of X-ray diffraction and Raman spectroscopy and no signs of phase transition were found up to 170 °C. Careful monitoring of the dependence of the XRD peak widths on the hkl indices showed that the effect of the cubic crystallite shape upon the XRD peak widths was buried by the effect of hidden tetragonal line splits and by anisotropic microstrain. The good correlation of the line widths with the tetragonal split amplitudes, observed especially for BTO-m above the transition temperature, indicates tetragonal deformations, as also revealed by Raman spectroscopy. The large anisotropic microstrain shown by the nano-powders, which had a maximum value in the <100> directions, was considered evidence of the phenomenon of surface relaxation of cubic crystallites edged by {100} faces. The observed behavior of the nano-BTO structures with increasing temperature may suggest a correlation between the surface relaxation and tetragonal deformation in the nano-cubes. The experimental results for both nano-BTO and mezoscale-BTO are in agreement with the core-shell model.
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Yang X, Li XM, Li Y, Li Y, Sun R, Liu JN, Bai X, Li N, Xie ZK, Su L, Gong ZZ, Zhang XQ, He W, Cheng Z. Three-Dimensional Limit of Bulk Rashba Effect in Ferroelectric Semiconductor GeTe. NANO LETTERS 2021; 21:77-83. [PMID: 33263408 DOI: 10.1021/acs.nanolett.0c03161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Ferroelectric Rashba semiconductors (FERSCs) have recently attracted intensive attention due to their giant bulk Rashba parameter, αR, which results in a locking between the spin degrees of freedom and the switchable electric polarization. However, the integration of FERSCs into microelectronic devices has provoked questions concerning whether the Rashba effect can persist when the material thickness is reduced to several nanometers. Here we find that αR can keep a large value of 2.12 eV Å in the 5.0 nm thick GeTe film. The behavior of αR with thickness can be expressed by the scaling law and provides a 3D thickness limit of the bulk Rashba effect, dc = 2.1 ± 0.5 nm. Finally, we find that the thickness can modify the Berry curvature as well, which influences the polarization and consequently alters the αR. Our results give insight into understanding the factors influencing αR in FERSCs and pave a novel route for designing Rashba-type quantum materials.
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Affiliation(s)
- Xu Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Mei Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rui Sun
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jia-Nan Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xuedong Bai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Na Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zong-Kai Xie
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Su
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zi-Zhao Gong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiang-Qun Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Wei He
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhaohua Cheng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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Urbain M, Riporto F, Beauquis S, Monnier V, Marty JC, Galez C, Durand C, Chevolot Y, Dantec RL, Mugnier Y. On the Reaction Pathways and Growth Mechanisms of LiNbO 3 Nanocrystals from the Non-Aqueous Solvothermal Alkoxide Route. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:E154. [PMID: 33435460 PMCID: PMC7828100 DOI: 10.3390/nano11010154] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/03/2021] [Accepted: 01/06/2021] [Indexed: 12/31/2022]
Abstract
Phase-pure, highly crystalline sub-50 nm LiNbO3 nanocrystals were prepared from a non-aqueous solvothermal process for 72 h at 230 °C and a commercial precursor solution of mixed lithium niobium ethoxide in its parent alcohol. A systematic variation of the reaction medium composition with the addition of different amounts of co-solvent including butanol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol resulted in the formation of nanocrystals of adjustable mean size and shape anisotropy, as demonstrated from XRD measurements and TEM imaging. Colloidal stability of ethanol- and water-based suspensions was evaluated from dynamic light scattering (DLS)/zeta potential studies and correlated with FTIR data. Thanks to the evolution in the nanocrystal size and shape distribution we observed, as well as to the available literature on the alkoxide chemistry, the reaction pathways and growth mechanisms were finally discussed with a special attention on the monomer formation rate, leading to the nucleation step. The polar, non-perovskite crystalline structure of LiNbO3 was also evidenced to play a major role in the nanocrystal shape anisotropy.
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Affiliation(s)
- Mathias Urbain
- SYMME, University of Savoie Mont Blanc, F-74000 Annecy, France; (M.U.); (F.R.); (S.B.); (J.-C.M.); (C.G.); (C.D.); (R.L.D.)
| | - Florian Riporto
- SYMME, University of Savoie Mont Blanc, F-74000 Annecy, France; (M.U.); (F.R.); (S.B.); (J.-C.M.); (C.G.); (C.D.); (R.L.D.)
| | - Sandrine Beauquis
- SYMME, University of Savoie Mont Blanc, F-74000 Annecy, France; (M.U.); (F.R.); (S.B.); (J.-C.M.); (C.G.); (C.D.); (R.L.D.)
| | - Virginie Monnier
- Institut des Nanotechnologies de Lyon (INL), UMR CNRS 5270, Ecole Centrale de Lyon, Université de Lyon, F-69134 Ecully CEDEX, France; (V.M.); (Y.C.)
| | - Jean-Christophe Marty
- SYMME, University of Savoie Mont Blanc, F-74000 Annecy, France; (M.U.); (F.R.); (S.B.); (J.-C.M.); (C.G.); (C.D.); (R.L.D.)
| | - Christine Galez
- SYMME, University of Savoie Mont Blanc, F-74000 Annecy, France; (M.U.); (F.R.); (S.B.); (J.-C.M.); (C.G.); (C.D.); (R.L.D.)
| | - Christiane Durand
- SYMME, University of Savoie Mont Blanc, F-74000 Annecy, France; (M.U.); (F.R.); (S.B.); (J.-C.M.); (C.G.); (C.D.); (R.L.D.)
| | - Yann Chevolot
- Institut des Nanotechnologies de Lyon (INL), UMR CNRS 5270, Ecole Centrale de Lyon, Université de Lyon, F-69134 Ecully CEDEX, France; (V.M.); (Y.C.)
| | - Ronan Le Dantec
- SYMME, University of Savoie Mont Blanc, F-74000 Annecy, France; (M.U.); (F.R.); (S.B.); (J.-C.M.); (C.G.); (C.D.); (R.L.D.)
| | - Yannick Mugnier
- SYMME, University of Savoie Mont Blanc, F-74000 Annecy, France; (M.U.); (F.R.); (S.B.); (J.-C.M.); (C.G.); (C.D.); (R.L.D.)
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Frolov AS, Sánchez-Barriga J, Callaert C, Hadermann J, Fedorov AV, Usachov DY, Chaika AN, Walls BC, Zhussupbekov K, Shvets IV, Muntwiler M, Amati M, Gregoratti L, Varykhalov AY, Rader O, Yashina LV. Atomic and Electronic Structure of a Multidomain GeTe Crystal. ACS NANO 2020; 14:16576-16589. [PMID: 33136362 DOI: 10.1021/acsnano.0c05851] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Renewed interest in the ferroelectric semiconductor germanium telluride was recently triggered by the direct observation of a giant Rashba effect and a 30-year-old dream about a functional spin field-effect transistor. In this respect, all-electrical control of the spin texture in this material in combination with ferroelectric properties at the nanoscale would create advanced functionalities in spintronics and data information processing. Here, we investigate the atomic and electronic properties of GeTe bulk single crystals and their (111) surfaces. We succeeded in growing crystals possessing solely inversion domains of ∼10 nm thickness parallel to each other. Using HAADF-TEM we observe two types of domain boundaries, one of them being similar in structure to the van der Waals gap in layered materials. This structure is responsible for the formation of surface domains with preferential Te-termination (∼68%) as we determined using photoelectron diffraction and XPS. The lateral dimensions of the surface domains are in the range of ∼10-100 nm, and both Ge- and Te-terminations reveal no reconstruction. Using spin-ARPES we establish an intrinsic quantitative relationship between the spin polarization of pure bulk states and the relative contribution of different terminations, a result that is consistent with a reversal of the spin texture of the bulk Rashba bands for opposite configurations of the ferroelectric polarization within individual nanodomains. Our findings are important for potential applications of ferroelectric Rashba semiconductors in nonvolatile spintronic devices with advanced memory and computing capabilities at the nanoscale.
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Affiliation(s)
- Alexander S Frolov
- Department of Chemistry, Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia
- Semenov Federal Research Center for Chemical Physics, Kosygina Street 4, 119991 Moscow, Russia
| | - Jaime Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Carolien Callaert
- EMAT, Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Joke Hadermann
- EMAT, Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Alexander V Fedorov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
- IFW Dresden, P.O. Box 270116, 01171 Dresden, Germany
- Joint Lab Functional Quantum Materials at BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Dmitry Yu Usachov
- St. Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia
| | - Alexander N Chaika
- Institute of Solid State Physics RAS, Academician Ossipyan Street 2, Chernogolovka, 142432 Moscow District, Russia
| | - Brian C Walls
- CRANN, School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | | | - Igor V Shvets
- CRANN, School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - Matthias Muntwiler
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Matteo Amati
- Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Basovizza, Trieste, Italy
| | - Luca Gregoratti
- Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Basovizza, Trieste, Italy
| | - Andrei Yu Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Oliver Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Lada V Yashina
- Department of Chemistry, Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia
- Semenov Federal Research Center for Chemical Physics, Kosygina Street 4, 119991 Moscow, Russia
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28
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Sun J, Li Q, Zhu H, Liu Z, Lin K, Wang N, Zhang Q, Gu L, Deng J, Chen J, Xing X. Negative-Pressure-Induced Large Polarization in Nanosized PbTiO 3. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2002968. [PMID: 33118254 DOI: 10.1002/adma.202002968] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 09/27/2020] [Indexed: 06/11/2023]
Abstract
Ferroelectric materials usually undergo decay with particle size decreasing into the nanoscale. At the critical value, the crystal structure undergoes a transition from the ferroelectric to paraelectric phase and the ferroelectricity vanishes. It is a big issue to sufficiently maintain strong ferroelectricity at the nanoscale. Herein, it is reported that synthesized 0D freestanding PbTiO3 nanoparticles (NPs) present negative pressure along the c axis (Δc/cbulk × 100% = -2.406), inducing large spontaneous polarization PS (71.2 µC cm-2 in 12 nm). Further local structural studies by atomic pair distribution functions and extended X-ray absorption fine structure indicate the structural evolution of nanosized PbTiO3 . High-angle annular dark-field STEM images reveal the existence of preponderant PbO-terminations on the surface of the PbTiO3 NPs. Ab initio calculation reveals the enhanced hybridization between Pb and O ions, which gives rise to the negative pressure and tensile stress to stabilize the high tetragonality and large polarization. The present work demonstrates an untraditional route to enhance the ferroelectricity and related properties in functional nanostructured materials, being of significance to nanodevices.
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Affiliation(s)
- Jing Sun
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China
| | - Qiang Li
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China
| | - He Zhu
- Department of Physics, City University of Hong Kong, Hong Kong, 999077, China
| | - Zhanning Liu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China
| | - Kun Lin
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China
| | - Na Wang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jinxia Deng
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jun Chen
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China
| | - Xianran Xing
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China
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Vankayala RK, Lan T, Parajuli P, Liu F, Rao R, Yu SH, Hung T, Lee C, Yano S, Hsing C, Nguyen D, Chen C, Bhattacharya S, Chen K, Ou M, Rancu O, Rao AM, Chen Y. High zT and Its Origin in Sb-doped GeTe Single Crystals. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2002494. [PMID: 33344133 PMCID: PMC7740100 DOI: 10.1002/advs.202002494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/10/2020] [Indexed: 05/14/2023]
Abstract
A record high zT of 2.2 at 740 K is reported in Ge0.92Sb0.08Te single crystals, with an optimal hole carrier concentration ≈4 × 1020 cm-3 that simultaneously maximizes the power factor (PF) ≈56 µW cm-1 K-2 and minimizes the thermal conductivity ≈1.9 Wm-1 K-1. In addition to the presence of herringbone domains and stacking faults, the Ge0.92Sb0.08Te exhibits significant modification to phonon dispersion with an extra phonon excitation around ≈5-6 meV at Γ point of the Brillouin zone as confirmed through inelastic neutron scattering (INS) measurements. Density functional theory (DFT) confirmed this phonon excitation, and predicted another higher energy phonon excitation ≈12-13 meV at W point. These phonon excitations collectively increase the number of phonon decay channels leading to softening of phonon frequencies such that a three-phonon process is dominant in Ge0.92Sb0.08Te, in contrast to a dominant four-phonon process in pristine GeTe, highlighting the importance of phonon engineering approaches to improving thermoelectric (TE) performance.
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Affiliation(s)
- Ranganayakulu K. Vankayala
- Institute of PhysicsAcademia SinicaTaipei11529Taiwan, ROC
- Dept. of Engineering and System ScienceNational Tsing Hua UniversityHsinchu30013Taiwan, ROC
- Taiwan International Graduate ProgramTaipei115Taiwan, ROC
| | - Tian‐Wey Lan
- Institute of PhysicsAcademia SinicaTaipei11529Taiwan, ROC
| | - Prakash Parajuli
- Clemson Nanomaterials InstituteDepartment of Physics and AstronomyClemson UniversityClemsonSC29634USA
| | - Fengjiao Liu
- Clemson Nanomaterials InstituteDepartment of Physics and AstronomyClemson UniversityClemsonSC29634USA
| | - Rahul Rao
- Air Force Research LaboratoryWPAFBDaytonOH45433USA
| | - Shih Hsun Yu
- Institute of PhysicsAcademia SinicaTaipei11529Taiwan, ROC
| | - Tsu‐Lien Hung
- Institute of PhysicsAcademia SinicaTaipei11529Taiwan, ROC
| | - Chih‐Hao Lee
- Dept. of Engineering and System ScienceNational Tsing Hua UniversityHsinchu30013Taiwan, ROC
| | - Shin‐ichiro Yano
- National Synchrotron Radiation Research CenterHsinchu30077Taiwan, ROC
| | - Cheng‐Rong Hsing
- Institute of Atomic and Molecular SciencesAcademia SinicaTaipei10617Taiwan, ROC
| | - Duc‐Long Nguyen
- Institute of Atomic and Molecular SciencesAcademia SinicaTaipei10617Taiwan, ROC
| | | | - Sriparna Bhattacharya
- Clemson Nanomaterials InstituteDepartment of Physics and AstronomyClemson UniversityClemsonSC29634USA
| | - Kuei‐Hsien Chen
- Institute of Atomic and Molecular SciencesAcademia SinicaTaipei10617Taiwan, ROC
| | - Min‐Nan Ou
- Institute of PhysicsAcademia SinicaTaipei11529Taiwan, ROC
| | - Oliver Rancu
- Clemson Nanomaterials InstituteDepartment of Physics and AstronomyClemson UniversityClemsonSC29634USA
| | - Apparao M. Rao
- Clemson Nanomaterials InstituteDepartment of Physics and AstronomyClemson UniversityClemsonSC29634USA
| | - Yang‐Yuan Chen
- Institute of PhysicsAcademia SinicaTaipei11529Taiwan, ROC
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Wu M, Ding T, Wang Y, Zhao W, Xian H, Tian Y, Zhang T, Li X. Rational construction of plasmon Au assisted ferroelectric-BaTiO3/Au/g-C3N4 Z-scheme system for efficient photocatalysis. Catal Today 2020. [DOI: 10.1016/j.cattod.2019.04.061] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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31
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Zhou X, Yan F, Wu S, Shen B, Zeng H, Zhai J. Remarkable Piezophoto Coupling Catalysis Behavior of BiOX/BaTiO 3 (X = Cl, Br, Cl 0.166 Br 0.834 ) Piezoelectric Composites. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2001573. [PMID: 32431007 DOI: 10.1002/smll.202001573] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 06/11/2023]
Abstract
Polarization field engineering of piezoelectric materials is considered as an advisable strategy in fine-tuning photocatalytic performance which has drawn much attention recently. However, the efficient charge separation that determines the photocatalytic reactivities of these materials is quite restricted. Herein, a judicious combination of piezoelectric and photocatalytic performances of BiOX/BaTiO3 (X = Cl, Br, Cl0.166 Br0.834 ) to enable a high piezophotocatalytic activity is demonstrated. Under the synergic advantages of chemical potential difference and piezoelectric potential difference in BiOX/BaTiO3 composites, the photoinduced carriers recombination is largely halted, which directly contributes to the significantly promoted piezophotocatalytic activity of piezoelectric composites. Inspiringly, the BiOBr/BaTiO3 composites under light irradiation with auxiliary ultrasonic activation result in an ultrahigh and stable photocatalytic performance, which is much higher than the total of those by isolated photocatalysis and piezocatalysis, and can rival current excellent photocatalytic system. In fact, the theoretical piezoelectric potential difference of BiOBr/BaTiO3 composites reaches 100 mV, which far exceeds the pure BaTiO3 of 31.21 mV and BiOBr of 30 mV, respectively. First, fabrication of BiOX/BaTiO3 piezoelectric composites and its remarkable piezophoto coupling catalysis behavior lays new ground for developing high-efficiency piezoelectric photocatalysts in purifying wastewater, killing bacteria, and other piezophototronic processes.
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Affiliation(s)
- Xiaofeng Zhou
- Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials, Functional Materials Research Laboratory, School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China
| | - Fei Yan
- Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials, Functional Materials Research Laboratory, School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China
| | - Shuanghao Wu
- Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials, Functional Materials Research Laboratory, School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China
| | - Bo Shen
- Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials, Functional Materials Research Laboratory, School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China
| | - Huarong Zeng
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Jiwei Zhai
- Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials, Functional Materials Research Laboratory, School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China
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32
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Song S, Lo CWT, Aminzare M, Tseng YC, Valiyaveettil SM, Mozharivskyj Y. Enhancing the thermoelectric performance of Sn 0.5Ge 0.5Te via doping with Sb/Bi and alloying with Cu 2Te: Optimization of transport properties and thermal conductivities. Dalton Trans 2020; 49:6135-6144. [PMID: 32328598 DOI: 10.1039/d0dt00544d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The current work provides a comparative study of the thermoelectric properties of the Sn0.5Ge0.5Te phases doped with Sb and Bi and alloyed with Cu2Te. The Sn0.5Ge0.5Te composition was chosen based on the fact that it delivers the highest ZT value within the Sn1-xGexTe series (x≤ 0.5). Doping Sn0.5Ge0.5Te with electron-richer Sb and Bi improves both the charge transport properties and thermal conductivities. Alloying with Cu2Te optimizes the thermoelectric performance of the samples even further, yielding a ZT value of 0.99 for (Sn0.5Ge0.5)0.91Bi0.06Te(Cu2Te)0.05 at 500 °C. Hall measurements were performed to understand the effects of doping and alloying.
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Affiliation(s)
- Shaochang Song
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada.
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33
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Chen S, Bai H, Li J, Pan W, Jiang X, Li Z, Chen Z, Yan Y, Su X, Wu J, Uher C, Tang X. Vacancy-Based Defect Regulation for High Thermoelectric Performance in Ge 9Sb 2Te 12-x Compounds. ACS APPLIED MATERIALS & INTERFACES 2020; 12:19664-19673. [PMID: 32255612 DOI: 10.1021/acsami.0c02155] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Defect engineering is the core strategy for improving thermoelectric properties. Herein, cation doping along with modulation of cation vacancy has been developed in GeTe-based materials as an effective method to induce vacancy-based defects to boost their thermoelectric performance. A series of ternary compounds of Ge9Sb2Te12-x (x = 0, 0.03, 0.06, 0.09, 0.12, 0.15) was prepared by vacuum-melting and annealing combined with the spark plasma sintering (SPS) process. The role of Sb doping and cation vacancy on thermoelectric properties was systematically investigated. It is found that alloying Sb2Te3 into GeTe increases the concentration of cation vacancies, which is corroborated by both positron annihilation measurements and theoretical calculations. The vacancies, stacking faults, and planar defect interactions determine the thermoelectric transport properties. Adjusting the deficiency of Te effectively tunes the concentration of cation vacancies and dopant defects in the structure. In turn, this tunes the carrier concentration close to its optimum. A high power factor of 32.6 μW cm-1 K-2 is realized for Ge9Sb2Te11.91 at 725 K. Moreover, large strains induced by the defect structures, including Sb dopant, vacancy, staking faults, as well as planar defects intensify phonon scattering, leading to a significant decrease in the thermal conductivity from 7.6 W m-1 K-1 for pristine GeTe to 1.18 W m-1 K-1 for Ge9Sb2Te11.85 at room temperature. All of the above contribute to a high ZT value of 2.1 achieved for the Ge9Sb2Te11.91 sample at 775 K.
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Affiliation(s)
- Shuo Chen
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Hui Bai
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Junjie Li
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Wenfeng Pan
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Xianyan Jiang
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Zhi Li
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Zhiquan Chen
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Yonggao Yan
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Xianli Su
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Jinsong Wu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Ctirad Uher
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Xinfeng Tang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
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Ab Initio Study of Ferroelectric Critical Size of SnTe Low-Dimensional Nanostructures. NANOMATERIALS 2020; 10:nano10040732. [PMID: 32290527 PMCID: PMC7221771 DOI: 10.3390/nano10040732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 04/03/2020] [Accepted: 04/08/2020] [Indexed: 11/23/2022]
Abstract
Beyond a ferroelectric critical thickness of several nanometers existed in conventional ferroelectric perovskite oxides, ferroelectricity in ultimately thin dimensions was recently discovered in SnTe monolayers. This discovery suggests the possibility that SnTe can sustain ferroelectricity during further low-dimensional miniaturization. Here, we investigate a ferroelectric critical size of low-dimensional SnTe nanostructures such as nanoribbons (1D) and nanoflakes (0D) using first-principle density-functional theory calculations. We demonstrate that the smallest (one-unit-cell width) SnTe nanoribbon can sustain ferroelectricity and there is no ferroelectric critical size in the SnTe nanoribbons. On the other hand, the SnTe nanoflakes form a vortex of polarization and lose their toroidal ferroelectricity below the surface area of 4 × 4 unit cells (about 25 Å on one side). We also reveal the atomic and electronic mechanism of the absence or presence of critical size in SnTe low-dimensional nanostructures. Our result provides an insight into intrinsic ferroelectric critical size for low-dimensional chalcogenide layered materials.
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35
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Campanini M, Erni R, Rossell MD. Probing local order in multiferroics by transmission electron microscopy. PHYSICAL SCIENCES REVIEWS 2020. [DOI: 10.1515/psr-2019-0068] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The ongoing trend toward miniaturization has led to an increased interest in the magnetoelectric effect, which could yield entirely new device concepts, such as electric field-controlled magnetic data storage. As a result, much work is being devoted to developing new robust room temperature (RT) multiferroic materials that combine ferromagnetism and ferroelectricity. However, the development of new multiferroic devices has proved unexpectedly challenging. Thus, a better understanding of the properties of multiferroic thin films and the relation with their microstructure is required to help drive multiferroic devices toward technological application. This review covers in a concise manner advanced analytical imaging methods based on (scanning) transmission electron microscopy which can potentially be used to characterize complex multiferroic materials. It consists of a first broad introduction to the topic followed by a section describing the so-called phase-contrast methods, which can be used to map the polar and magnetic order in magnetoelectric multiferroics at different spatial length scales down to atomic resolution. Section 3 is devoted to electron nanodiffraction methods. These methods allow measuring local strains, identifying crystal defects and determining crystal structures, and thus offer important possibilities for the detailed structural characterization of multiferroics in the ultrathin regime or inserted in multilayers or superlattice architectures. Thereafter, in Section 4, methods are discussed which allow for analyzing local strain, whereas in Section 5 methods are addressed which allow for measuring local polarization effects on a length scale of individual unit cells. Here, it is shown that the ferroelectric polarization can be indirectly determined from the atomic displacements measured in atomic resolution images. Finally, a brief outlook is given on newly established methods to probe the behavior of ferroelectric and magnetic domains and nanostructures during in situ heating/electrical biasing experiments. These in situ methods are just about at the launch of becoming increasingly popular, particularly in the field of magnetoelectric multiferroics, and shall contribute significantly to understanding the relationship between the domain dynamics of multiferroics and the specific microstructure of the films providing important guidance to design new devices and to predict and mitigate failures.
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Caruntu D, Kavey B, Paul S, Bas AC, Rotaru A, Caruntu G. Dielectric properties of solution-processed BaTiO3–styrene butadiene styrene nanocomposite films. CrystEngComm 2020. [DOI: 10.1039/c9ce01912j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Polymer–ceramic nanocomposite films comprising ceramic nanoparticles dispersed in a polymer matrix (0–3 composites) have garnered increasing interest due to their superior performance characteristics, and can be used in flexible modern electronics and energy storage systems.
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Affiliation(s)
- Daniela Caruntu
- Department of Chemistry and Biochemistry
- Central Michigan University
- Mount Pleasant
- USA
- Department of Electrical Engineering and Computer Science and MANSID Research Center
| | - Benard Kavey
- Department of Chemistry and Biochemistry
- Central Michigan University
- Mount Pleasant
- USA
- Science of Advanced Materials Program
| | - Suporna Paul
- Department of Chemistry and Biochemistry
- Central Michigan University
- Mount Pleasant
- USA
| | - Alin Ciprian Bas
- Department of Electrical Engineering and Computer Science and MANSID Research Center
- “Stefan Cel Mare” University
- Romania
| | - Aurelian Rotaru
- Department of Electrical Engineering and Computer Science and MANSID Research Center
- “Stefan Cel Mare” University
- Romania
| | - Gabriel Caruntu
- Department of Chemistry and Biochemistry
- Central Michigan University
- Mount Pleasant
- USA
- Science of Advanced Materials Program
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Samanta M, Ghosh T, Arora R, Waghmare UV, Biswas K. Realization of Both n- and p-Type GeTe Thermoelectrics: Electronic Structure Modulation by AgBiSe 2 Alloying. J Am Chem Soc 2019; 141:19505-19512. [PMID: 31735034 DOI: 10.1021/jacs.9b11405] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Successful applications of a thermoelectric material require simultaneous development of compatible n- and p-type counterparts. While the thermoelectric performance of p-type GeTe has been improved tremendously in recent years, it has been a challenge to find a compatible n-type GeTe counterpart due to the prevalence of intrinsic Ge vacancies. Herein, we have shown that alloying of AgBiSe2 with GeTe results in an intriguing evolution in its crystal and electronic structures, resulting in n-type thermoelectric properties. We have demonstrated that the ambient rhombohedral structure of pristine GeTe transforms into cubic phase in (GeTe)100-x(AgBiSe2)x for x ≥ 25, with concurrent change from its p-type electronic character to n-type character in electronic transport properties. Such change in structural and electronic properties is confirmed from the nonmonotonic variation of band gap, unit cell volume, electrical conductivity, and Seebeck coefficient, all of which show an inflection point around x ∼ 20, as well as from the temperature variations of synchrotron powder X-ray diffractions and differential scanning calorimetry. First-principles density functional theoretical (DFT) calculations explain that the shift toward n-type electronic character with increasing AgBiSe2 concentration arises due to increasing contribution of Bi p orbitals in the conduction band edge of (GeTe)100-x(AgBiSe2)x. This cubic n-type phase has promising thermoelectric properties with a band gap of ∼0.25 eV and ultralow lattice thermal conductivity that ranges between 0.3 and 0.6 W/mK. Further, we have shown that (GeTe)100-x(AgBiSe2)x has promising thermoelectric performance in the mid-temperature range (400-500 K) with maximum thermoelectric figure of merit, zT, reaching ∼1.3 in p-type (GeTe)80(AgBiSe2)20 at 467 K and ∼0.6 in n-type (GeTe)50(AgBiSe2)50 at 500 K.
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Su R, Hsain HA, Wu M, Zhang D, Hu X, Wang Z, Wang X, Li F, Chen X, Zhu L, Yang Y, Yang Y, Lou X, Pennycook SJ. Nano‐Ferroelectric for High Efficiency Overall Water Splitting under Ultrasonic Vibration. Angew Chem Int Ed Engl 2019; 58:15076-15081. [DOI: 10.1002/anie.201907695] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Indexed: 01/08/2023]
Affiliation(s)
- Ran Su
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - H. Alex Hsain
- Materials Science and Engineering North Carolina State University Raleigh NC 27695 USA
| | - Ming Wu
- Frontier Institute of Science and Technology State Key Laboratory for Mechanical behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
| | - Dawei Zhang
- School of Materials Science and Engineering University of New South Wales Sydney New South Wales 2052 Australia
| | - Xinghao Hu
- Micro/Nano Science and Technology Center Jiangsu University Zhenjiang 212013 China
| | - Zhipeng Wang
- Department of Energy Science Sungkyunkwan University Suwon 16419 Republic of Korea
| | - Xiaojing Wang
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Fa‐tang Li
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Xuemin Chen
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Lina Zhu
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Yong Yang
- State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal Materials Northwestern Polytechnical University Xi'an 710072 China
| | - Yaodong Yang
- Frontier Institute of Science and Technology State Key Laboratory for Mechanical behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
| | - Xiaojie Lou
- Frontier Institute of Science and Technology State Key Laboratory for Mechanical behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
| | - Stephen J. Pennycook
- Department of Materials Science and Engineering Faculty of Engineering National University of Singapore Singapore 117574 Singapore
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39
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Su R, Hsain HA, Wu M, Zhang D, Hu X, Wang Z, Wang X, Li F, Chen X, Zhu L, Yang Y, Yang Y, Lou X, Pennycook SJ. Nano‐Ferroelectric for High Efficiency Overall Water Splitting under Ultrasonic Vibration. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201907695] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ran Su
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - H. Alex Hsain
- Materials Science and Engineering North Carolina State University Raleigh NC 27695 USA
| | - Ming Wu
- Frontier Institute of Science and Technology State Key Laboratory for Mechanical behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
| | - Dawei Zhang
- School of Materials Science and Engineering University of New South Wales Sydney New South Wales 2052 Australia
| | - Xinghao Hu
- Micro/Nano Science and Technology Center Jiangsu University Zhenjiang 212013 China
| | - Zhipeng Wang
- Department of Energy Science Sungkyunkwan University Suwon 16419 Republic of Korea
| | - Xiaojing Wang
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Fa‐tang Li
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Xuemin Chen
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Lina Zhu
- College of Science Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Yong Yang
- State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal Materials Northwestern Polytechnical University Xi'an 710072 China
| | - Yaodong Yang
- Frontier Institute of Science and Technology State Key Laboratory for Mechanical behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
| | - Xiaojie Lou
- Frontier Institute of Science and Technology State Key Laboratory for Mechanical behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
| | - Stephen J. Pennycook
- Department of Materials Science and Engineering Faculty of Engineering National University of Singapore Singapore 117574 Singapore
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40
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Ferroelectric Polarization-Enhanced Photocatalysis in BaTiO 3-TiO 2 Core-Shell Heterostructures. NANOMATERIALS 2019; 9:nano9081116. [PMID: 31382577 PMCID: PMC6722819 DOI: 10.3390/nano9081116] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 07/28/2019] [Accepted: 07/30/2019] [Indexed: 11/25/2022]
Abstract
Suppressing charge recombination and improving carrier transport are key challenges for the enhancement of photocatalytic activity of heterostructured photocatalysts. Here, we report a ferroelectric polarization-enhanced photocatalysis on the basis of BaTiO3-TiO2 core-shell heterostructures synthesized via a hydrothermal process. With an optimal weight ratio of BaTiO3 to TiO2, the heterostructures exhibited the maximum photocatalytic performance of 1.8 times higher than pure TiO2 nanoparticles. The enhanced photocatalytic activity is attributed to the promotion of charge separation and transport based on the internal electric field originating from the spontaneous polarization of ferroelectric BaTiO3. High stability of polarization-enhanced photocatalysis is also confirmed from the BaTiO3-TiO2 core-shell heterostructures. This study provides evidence that ferroelectric polarization holds great promise for improving the performance of heterostructured photocatalysts.
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41
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Zablotsky D, Rusevich LL, Zvejnieks G, Kuzovkov V, Kotomin E. Manifestation of dipole-induced disorder in self-assembly of ferroelectric and ferromagnetic nanocubes. NANOSCALE 2019; 11:7293-7303. [PMID: 30938394 DOI: 10.1039/c9nr00708c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The colloidal processing of nearly monodisperse and highly crystalline single-domain ferroelectric or ferromagnetic nanocubes is a promising route to produce superlattice structures for integration into next-generation devices, whereas controlling the local behaviour of nanocrystals is imperative for fabricating highly-ordered assemblies. The current picture of nanoscale polarization in individual nanocrystals suggests a potential presence of a significant dipolar interaction, but its role in the condensation of nanocubes is unknown. We simulate the self-assembly of colloidal dipolar nanocubes under osmotic compression and perform the microstructural characterization of their densified ensembles. Our results indicate that the long-range positional and orientational correlations of perovskite nanocubes are highly sensitive to the presence of dipoles.
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Affiliation(s)
- Dmitry Zablotsky
- Institute of Solid State Physics, Kengaraga str. 8, LV-1063 Riga, Latvia
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42
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Kim Y, Che F, Jo JW, Choi J, García de Arquer FP, Voznyy O, Sun B, Kim J, Choi MJ, Quintero-Bermudez R, Fan F, Tan CS, Bladt E, Walters G, Proppe AH, Zou C, Yuan H, Bals S, Hofkens J, Roeffaers MBJ, Hoogland S, Sargent EH. A Facet-Specific Quantum Dot Passivation Strategy for Colloid Management and Efficient Infrared Photovoltaics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1805580. [PMID: 30860292 DOI: 10.1002/adma.201805580] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 02/24/2019] [Indexed: 06/09/2023]
Abstract
Colloidal nanocrystals combine size- and facet-dependent properties with solution processing. They offer thus a compelling suite of materials for technological applications. Their size- and facet-tunable features are studied in synthesis; however, to exploit their features in optoelectronic devices, it will be essential to translate control over size and facets from the colloid all the way to the film. Larger-diameter colloidal quantum dots (CQDs) offer the attractive possibility of harvesting infrared (IR) solar energy beyond absorption of silicon photovoltaics. These CQDs exhibit facets (nonpolar (100)) undisplayed in small-diameter CQDs; and the materials chemistry of smaller nanocrystals fails consequently to translate to materials for the short-wavelength IR regime. A new colloidal management strategy targeting the passivation of both (100) and (111) facets is demonstrated using distinct choices of cations and anions. The approach leads to narrow-bandgap CQDs with impressive colloidal stability and photoluminescence quantum yield. Photophysical studies confirm a reduction both in Stokes shift (≈47 meV) and Urbach tail (≈29 meV). This approach provides a ≈50% increase in the power conversion efficiency of IR photovoltaics compared to controls, and a ≈70% external quantum efficiency at their excitonic peak.
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Affiliation(s)
- Younghoon Kim
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Fanglin Che
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Jea Woong Jo
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Jongmin Choi
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - F Pelayo García de Arquer
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Oleksandr Voznyy
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Bin Sun
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Junghwan Kim
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Min-Jae Choi
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Rafael Quintero-Bermudez
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Fengjia Fan
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Chih Shan Tan
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Eva Bladt
- Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium
| | - Grant Walters
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Andrew H Proppe
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Chengqin Zou
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Haifeng Yuan
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
- Departement of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001, Heverlee, Belgium
| | - Sara Bals
- Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium
| | - Johan Hofkens
- Departement of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001, Heverlee, Belgium
| | - Maarten B J Roeffaers
- Center for Surface Chemistry and Catalysis, Faculty of Bioscience Engineering, KU Leuven, 3001, Heverlee, Belgium
| | - Sjoerd Hoogland
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Edward H Sargent
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
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Barnakov YA, Idehenre IU, Basun SA, Tyson TA, Evans DR. Uncovering the mystery of ferroelectricity in zero dimensional nanoparticles. NANOSCALE ADVANCES 2019; 1:664-670. [PMID: 36132233 PMCID: PMC9473165 DOI: 10.1039/c8na00131f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 10/23/2018] [Indexed: 06/11/2023]
Abstract
It is generally accepted that chemically synthesized nanoparticles lose their ferroelectricity (spontaneous polarization) as the particles become smaller. In contrast, ball-milled ferroelectric nanoparticles have an enhanced ferroelectric response at remarkably small sizes (≤10 nm). Although prior theory suggests that surface stress influences ferroelectricity, the source of such a stress and how it physically influences ferroelectricity in zero-dimensional nanoparticles has remained a mystery. In this paper, we demonstrate that the top-down approach of wet ball-milling not only results in fragmented materials on the nanoscale, but it also is responsible for a mechanochemical synthesis of metal carboxylates forming at the nanoparticles' surface. We prove that the presence of such a compound with a particular type of binding mode chemisorbed at the nanoparticles' surface is responsible for producing surface stress. This surface stress results in a stabilization and dramatic enhancement of the spontaneous polarization, which is 5 times greater than that of the bulk material and 650 times greater than what is measured in materials fabricated using standard chemical synthesis techniques. The results of this study have further led to the development of a new process that produces ferroelectric nanoparticles (≤10 nm) with uniform shape and size using a combination of wet chemistry and mechanochemical synthesis.
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Affiliation(s)
- Yury A Barnakov
- Air Force Research Laboratory, Materials and Manufacturing Directorate Wright-Patterson Air Force Base Ohio 45433 USA
- Azimuth Corporation 4027 Colonel Glenn Highway, Suite 230 Beavercreek Ohio 45431 USA
| | - Ighodalo U Idehenre
- Air Force Research Laboratory, Materials and Manufacturing Directorate Wright-Patterson Air Force Base Ohio 45433 USA
- University of Dayton, Department of Electro-Optics and Photonics Dayton Ohio 45469 USA
| | - Sergey A Basun
- Air Force Research Laboratory, Materials and Manufacturing Directorate Wright-Patterson Air Force Base Ohio 45433 USA
- Azimuth Corporation 4027 Colonel Glenn Highway, Suite 230 Beavercreek Ohio 45431 USA
| | - Trevor A Tyson
- Department of Physics, New Jersey Institute of Technology Newark NJ 07102 USA
| | - Dean R Evans
- Air Force Research Laboratory, Materials and Manufacturing Directorate Wright-Patterson Air Force Base Ohio 45433 USA
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Hawken SL, Huang R, de Groot CH(K, Hector AL, Jura M, Levason W, Reid G, Stenning GBG. [Ge(Te nBu) 4] – a single source precursor for the chemical vapour deposition of germanium telluride thin films. Dalton Trans 2019; 48:117-124. [DOI: 10.1039/c8dt03263g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Reaction of activated germanium with nBu2Te2 in THF solution was shown to be more effective for the preparation of the germanium(iv) tellurolate compound, [Ge(TenBu)4], than reaction of GeCl4 with LiTenBu in THF.
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Affiliation(s)
| | - Ruomeng Huang
- School of Electronics and Computer Science
- University of Southampton
- Southampton SO17 1BJ
- UK
| | - C. H. (Kees) de Groot
- School of Electronics and Computer Science
- University of Southampton
- Southampton SO17 1BJ
- UK
| | - Andrew L. Hector
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
| | - Marek Jura
- ISIS Neutron and Muon Source
- Rutherford Appleton Laboratory
- Harwell Science and Innovation Campus
- Didcot
- UK
| | - William Levason
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
| | - Gillian Reid
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
| | - Gavin B. G. Stenning
- ISIS Neutron and Muon Source
- Rutherford Appleton Laboratory
- Harwell Science and Innovation Campus
- Didcot
- UK
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45
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Huang F, Hu C, Tian H, Meng X, Tan P, Zhou Z. Controllable anisotropic characteristics in solid solution ferroelectrics. CrystEngComm 2019. [DOI: 10.1039/c9ce01198f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Controllable anisotropic properties by adjusting the anisotropic composition gradients in KTN single crystals.
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Affiliation(s)
- Fei Huang
- School of Physics
- Harbin Institute of Technology
- Harbin 150001
- China
| | - Chengpeng Hu
- School of Physics
- Harbin Institute of Technology
- Harbin 150001
- China
| | - Hao Tian
- School of Physics
- Harbin Institute of Technology
- Harbin 150001
- China
| | - Xiangda Meng
- School of Physics
- Harbin Institute of Technology
- Harbin 150001
- China
| | - Peng Tan
- School of Physics
- Harbin Institute of Technology
- Harbin 150001
- China
| | - Zhongxiang Zhou
- School of Physics
- Harbin Institute of Technology
- Harbin 150001
- China
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Fang T, Jie Y, Huang Y, Ye YH, Chen WB, Li BQ, Zou C, Xu DL, Qian K. Above Room Temperature Organic Dielectric Switchable Material: Diprotonated 1,4-Diazabicyclo[2.2.2]octane Shifts between Two Pyruvic Acids. Z Anorg Allg Chem 2018. [DOI: 10.1002/zaac.201800362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Ting Fang
- College of Pharmacy; Jiangxi University of Traditional Chinese Medicine; 330004 Nanchang P. R. China
| | - Yang Jie
- College of Pharmacy; Jiangxi University of Traditional Chinese Medicine; 330004 Nanchang P. R. China
| | - Yuan Huang
- College of Pharmacy; Jiangxi University of Traditional Chinese Medicine; 330004 Nanchang P. R. China
| | - Yao-Hui Ye
- The Office of Academic Affairs; Jiangxi University of Traditional Chinese Medicine; 330004 Nanchang P. R. China
| | - Wen-Bin Chen
- College of Pharmacy; Jiangxi University of Traditional Chinese Medicine; 330004 Nanchang P. R. China
| | - Bing-Qi Li
- College of Pharmacy; Jiangxi University of Traditional Chinese Medicine; 330004 Nanchang P. R. China
| | - Chen Zou
- College of Pharmacy; Jiangxi University of Traditional Chinese Medicine; 330004 Nanchang P. R. China
| | - Dan-Lei Xu
- College of Pharmacy; Jiangxi University of Traditional Chinese Medicine; 330004 Nanchang P. R. China
| | - Kun Qian
- College of Pharmacy; Jiangxi University of Traditional Chinese Medicine; 330004 Nanchang P. R. China
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47
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Zong Y, Yue Z, Martins P, Zhuang J, Du Y, Lanceros-Mendez S, Higgins MJ. Magnetoelectric coupling in nanoscale 0-1 connectivity. NANOSCALE 2018; 10:17370-17377. [PMID: 30203827 DOI: 10.1039/c8nr05182h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The strain-mediated magnetoelectric (ME) coupling between piezoelectric (PE) and magnetostrictive (MS) components are established in various connectivities. Discovering new ME connectivity and elucidating the key factors governing the performance of ME composite are of critical importance to find advanced materials for modern electronics. Reported here is a novel ME coupling in 0-1 connectivity. The unique self-assembling ability of 1-dimension crystalline nanocellulose (CNC) nanowhiskers enables the establishment of ME coupling with 0-dimension cobalt ferrite (CFO) nanoparticles without the use of binder. The developed CFO/CNC 0-1 ME composites display a significant ME voltage coefficient (αME) as high as 0.135 mV cm-1 Oe-1. The CFO nanoparticles are also modified with a cationic surfactant, cetyltrimethylammonium bromide (CTAB), to reduce their dispersion ability. A ME response related to the rearrangement of aggregated MS nanoparticles is observed in the CTAB-CFO/CNC composites, which differs from the typical magnetostriction induced ME effect in nanoparticulate ME composites.
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Affiliation(s)
- Yan Zong
- ARC Centre for Electromaterials Science (ACES), Intelligent Polymer Research Institute/AIIM Faculty, Innovation Campus, Squires Way, University of Wollongong, NSW 2522, Australia.
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48
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Ming WQ, Chen JH, He YT, Shen RH, Chen ZK. An improved iterative wave function reconstruction algorithm in high-resolution transmission electron microscopy. Ultramicroscopy 2018; 195:111-120. [PMID: 30227297 DOI: 10.1016/j.ultramic.2018.09.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 08/26/2018] [Accepted: 09/04/2018] [Indexed: 10/28/2022]
Abstract
Exit wavefunction reconstruction is a powerful image processing technique to enhance the resolution and the signal-to-noise ratio for atomic-resolution imaging in both aberration uncorrected and corrected transmission electron microscopes. The present study aims to improve the performance of the iterative wavefunction reconstruction algorithm in comparison not only with its conventional form but also with the popular commercial Trueimage software for exit wavefunction reconstruction. It is shown that by implementing a wave propagation procedure for refining its image alignment, the iterative wavefunction reconstruction algorithm can be greatly improved in accurately retrieving the wavefunctions while keeping its original advantages, which allow the reconstruction be performed with less images and a larger defocus step in the data set of through-focus image series. In addition, calculations of this algorithm can be accelerated drastically by the graphic processing unit (GPU) hardware programming using the popular computer unified device architecture language, whose computing speed can be 25-38 times as fast as a central processing unit (CPU) program.
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Affiliation(s)
- W Q Ming
- College of Materials Science and Engineering, Centre for High Resolution Electron Microscopy, Hunan University, Changsha 410082, China
| | - J H Chen
- College of Materials Science and Engineering, Centre for High Resolution Electron Microscopy, Hunan University, Changsha 410082, China.
| | - Y T He
- College of Materials Science and Engineering, Centre for High Resolution Electron Microscopy, Hunan University, Changsha 410082, China
| | - R H Shen
- College of Materials Science and Engineering, Centre for High Resolution Electron Microscopy, Hunan University, Changsha 410082, China
| | - Z K Chen
- College of Materials Science and Engineering, Centre for High Resolution Electron Microscopy, Hunan University, Changsha 410082, China
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49
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Bertolotti F, Moscheni D, Guagliardi A, Masciocchi N. When Crystals Go Nano - The Role of Advanced X-ray Total Scattering Methods in Nanotechnology. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800534] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Federica Bertolotti
- Aarhus Institute of Advanced Studies (AIAS); Aarhus University; Høegh-Guldbergs Gade 6B 8000 Aarhus C Denmark
- Department of Science and High Technology and To.Sca.Lab. University of Insubria; Via Valleggio 11 22100 Como Italy
| | - Daniele Moscheni
- Department of Science and High Technology and To.Sca.Lab. University of Insubria; Via Valleggio 11 22100 Como Italy
| | - Antonietta Guagliardi
- Institute of Crystallography and To.Sca.Lab.; Consiglio Nazionale delle Ricerche; Via Valleggio 11 22100 Como Italy
| | - Norberto Masciocchi
- Department of Science and High Technology and To.Sca.Lab. University of Insubria; Via Valleggio 11 22100 Como Italy
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50
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Giant magnetoelectric effect at the graphone/ferroelectric interface. Sci Rep 2018; 8:12448. [PMID: 30127515 PMCID: PMC6102284 DOI: 10.1038/s41598-018-30010-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 07/16/2018] [Indexed: 11/08/2022] Open
Abstract
Multiferroic heterostructures combining ferromagnetic and ferroelectric layers are promising for applications in novel spintronic devices, such as memories with electrical writing and magnetic reading, assuming their magnetoelectric coupling (MEC) is strong enough. For conventional magnetic metal/ferroelectric heterostructures, however, the change of interfacial magnetic moment upon reversal of the electric polarization is often very weak. Here, by using first principles calculations, we demonstrate a new pathway towards a strong MEC at the interface between the semi-hydrogenated graphene (also called graphone) and ferroelectric PbTiO3. By reversing the polarization of PbTiO3, the magnetization of graphone can be electrically switched on and off through the change of carbon-oxygen bonding at the interface. Furthermore, a ferroelectric polarization can be preserved down to ultrathin PbTiO3 layers less than one nanometer due to an enhancement of the polarization at the interface. The predicted strong magnetoelectric effect in the ultimately thin graphone/ferroelectric layers opens a new opportunity for the electric control of magnetism in high-density devices.
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