1
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Fan D, Naskar S, Maurin G. Unconventional mechanical and thermal behaviours of MOF CALF-20. Nat Commun 2024; 15:3251. [PMID: 38627391 PMCID: PMC11021538 DOI: 10.1038/s41467-024-47695-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 04/05/2024] [Indexed: 04/19/2024] Open
Abstract
CALF-20 was recently identified as a benchmark sorbent for CO2 capture at the industrial scale, however comprehensive atomistic insight into its mechanical/thermal properties under working conditions is still lacking. In this study, we developed a general-purpose machine-learned potential (MLP) for the CALF-20 MOF framework that predicts the thermodynamic and mechanical properties of the structure at finite temperatures within first-principles accuracy. Interestingly, CALF-20 was demonstrated to exhibit both negative area compression and negative thermal expansion. Most strikingly, upon application of the tensile strain along the [001] direction, CALF-20 was shown to display a distinct two-step elastic deformation behaviour, unlike typical MOFs that undergo plastic deformation after elasticity. Furthermore, this MOF was shown to exhibit a fracture strain of up to 27% along the [001] direction at room temperature comparable to that of MOF glasses. These abnormal thermal and mechanical properties make CALF-20 as attractive material for flexible and stretchable electronics and sensors.
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Affiliation(s)
- Dong Fan
- ICGM, Univ. Montpellier, CNRS, ENSCM, Montpellier, 34095, France
- School of Materials Science and Engineering, Chongqing Jiaotong University, Chongqing, 400074, PR China
| | - Supriyo Naskar
- ICGM, Univ. Montpellier, CNRS, ENSCM, Montpellier, 34095, France
| | - Guillaume Maurin
- ICGM, Univ. Montpellier, CNRS, ENSCM, Montpellier, 34095, France.
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2
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Han Y, Wang L, Cao K, Zhou J, Zhu Y, Hou Y, Lu Y. In Situ TEM Characterization and Modulation for Phase Engineering of Nanomaterials. Chem Rev 2023; 123:14119-14184. [PMID: 38055201 DOI: 10.1021/acs.chemrev.3c00510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Solid-state phase transformation is an intriguing phenomenon in crystalline or noncrystalline solids due to the distinct physical and chemical properties that can be obtained and modified by phase engineering. Compared to bulk solids, nanomaterials exhibit enhanced capability for phase engineering due to their small sizes and high surface-to-volume ratios, facilitating various emerging applications. To establish a comprehensive atomistic understanding of phase engineering, in situ transmission electron microscopy (TEM) techniques have emerged as powerful tools, providing unprecedented atomic-resolution imaging, multiple characterization and stimulation mechanisms, and real-time integrations with various external fields. In this Review, we present a comprehensive overview of recent advances in in situ TEM studies to characterize and modulate nanomaterials for phase transformations under different stimuli, including mechanical, thermal, electrical, environmental, optical, and magnetic factors. We briefly introduce crystalline structures and polymorphism and then summarize phase stability and phase transformation models. The advanced experimental setups of in situ techniques are outlined and the advantages of in situ TEM phase engineering are highlighted, as demonstrated via several representative examples. Besides, the distinctive properties that can be obtained from in situ phase engineering are presented. Finally, current challenges and future research opportunities, along with their potential applications, are suggested.
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Affiliation(s)
- Ying Han
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR 999077, China
| | - Liqiang Wang
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR 999077, China
| | - Ke Cao
- School of Advanced Materials and Nanotechnology, Xidian University, Xi'an, Shaanxi 710026, China
| | - Jingzhuo Zhou
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR 999077, China
| | - Yingxin Zhu
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR 999077, China
| | - Yuan Hou
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR 999077, China
| | - Yang Lu
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR 999077, China
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3
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Volnianska O, Ivanov V, Wachnicki L, Guziewicz E. Effect of Strain and Surface Proximity on the Acceptor Grouping in ZnO. ACS OMEGA 2023; 8:43099-43108. [PMID: 38024714 PMCID: PMC10652265 DOI: 10.1021/acsomega.3c06556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/13/2023] [Accepted: 10/19/2023] [Indexed: 12/01/2023]
Abstract
According to the present knowledge, the level of zinc oxide conductivity is determined by donor and acceptor complexes involving native defects and hydrogen. In turn, recently published low-temperature cathodoluminescence images and scanning photoelectron microscopy results on ZnO and ZnO/N films indicate grouping of acceptor and donor complexes in different crystallites, but the origin of this phenomenon remains unclear. The density functional theory calculations on undoped ZnO presented here show that strain and surface proximity noticeably influence the formation energy of acceptor complexes, and therefore, these complexes can be more easily formed in crystallites providing appropriate strain. This effect may be responsible for the clustering of acceptor centers only in certain crystallites or near the surface. Low-temperature photoluminescence spectra confirm the strong dependence of acceptor luminescence on the structure of the ZnO film.
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Affiliation(s)
- Oksana Volnianska
- Institute of Physics, Polish
Academy of Sciences, 02-668 Warsaw, Poland
| | - Vitalii Ivanov
- Institute of Physics, Polish
Academy of Sciences, 02-668 Warsaw, Poland
| | - Lukasz Wachnicki
- Institute of Physics, Polish
Academy of Sciences, 02-668 Warsaw, Poland
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4
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Zhang J. Phase transformation and its effect on the piezopotential in a bent zinc oxide nanowire. NANOTECHNOLOGY 2021; 32:075404. [PMID: 33105120 DOI: 10.1088/1361-6528/abc49f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Most piezotronic nanodevices rely on the piezopotential generated by the bending of their component piezoelectric nanowires (NWs). The mechanical behaviours and piezopotential properties of zinc oxide (ZnO) NWs under lateral bending are investigated in this paper by using a multiscale modelling technique combining first-principles calculations, molecular dynamics simulations and finite-element calculations. Two phase transformation processes are successively found in ZnO NWs by increasing the bending force. As a result, the inner and outer surfaces of bent ZnO NWs transform from the parent wurtzite (WZ) structure to a hexagonal (HX) structure and a body-centred-tetragonal (BCT-4) structure, respectively. Different material properties are found among the WZ, BCT-4, and HX structures, which result in a significant change in the piezopotential distribution in bent ZnO NWs after the phase transformation. Meanwhile, the piezopotential generated in bent ZnO NWs can be enhanced by an order of magnitude due to the phase transformation. Moreover, a significant increase in the electronic band gap is found in the transformed HX structure, which implies that the phase transformation may also affect the piezopotential in bent ZnO NWs by modifying their semiconducting properties especially when the doping level of NWs is large.
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Affiliation(s)
- Jin Zhang
- School of Science, Harbin Institute of Technology, Shenzhen 518055, People's Republic of China
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5
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Zahoor R, Jalil A, Ilyas SZ, Ahmed S, Hassan A. Optoelectronic and solar cell applications of ZnO nanostructures. RESULTS IN SURFACES AND INTERFACES 2021. [DOI: 10.1016/j.rsurfi.2021.100003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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6
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Tawfik SA, Osborne DA, Spencer MJS. Theoretical insight on the origin of anelasticity in zinc oxide nanowires. NANOSCALE 2020; 12:2439-2444. [PMID: 31840703 DOI: 10.1039/c9nr07901g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Anelasticity of nanowires has recently attracted attention as an interesting property for high efficiency mechanical damping materials. While the mechanism of anelasticity has so far been analysed using continuum mechanical models based on defect diffusion, the mechanisms behind anelasticity have not yet been determined on an atomic level. Such information is needed in order to be able to design and synthesise new nanomaterials having desired mechanical properties. Here we determine the potential mechanism of anelasticity in narrow zinc oxide nanowires by analyzing the bond stretching and compression within the nanowire structure based on density functional theory. Our approach shows that different local minimum structures are created when different strain patterns are applied which give rise to the anelastic behavior. These findings can be applied for the prediction of potential anelasticity of other nanowire materials.
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Affiliation(s)
| | - Dale A Osborne
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia.
| | - Michelle J S Spencer
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia.
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7
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Zhao P, Guan X, Zheng H, Jia S, Li L, Liu H, Zhao L, Sheng H, Meng W, Zhuang Y, Wu J, Li L, Wang J. Surface- and Strain-Mediated Reversible Phase Transformation in Quantum-Confined ZnO Nanowires. PHYSICAL REVIEW LETTERS 2019; 123:216101. [PMID: 31809167 DOI: 10.1103/physrevlett.123.216101] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Indexed: 06/10/2023]
Abstract
The phase stability of ZnO in a quantum-confinement size regime (sub-2-nm) remains fiercely debated. Applying in situ (scanning) transmission electron microscopy, we present the atomistic view of the phase transitions from the original wurtzite structure to an intermediate body-centered tetragonal and h-MgO structure under tensile strain in quantum-confined ZnO nanowires. Strikingly, such structural transitions are reversible after releasing the stress. Further theoretical calculations mirror the transition pathway and provide basic insight into the overall landscape regarding surface- and strain-dependent phase transition behavior. Our results provide the critical piece to solve the puzzle in phase stability of ZnO, which may prove essential for advancing a variety of nanotechnologies, e.g., quantum-dot light-emitting devices.
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Affiliation(s)
- Peili Zhao
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Xiaoxi Guan
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - He Zheng
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Shuangfeng Jia
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Lei Li
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Huihui Liu
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Lulu Zhao
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Huaping Sheng
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Weiwei Meng
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Yuanlin Zhuang
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Jiangbing Wu
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Luying Li
- Center for Nanoscale Characterization & Devices, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Jianbo Wang
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
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8
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Wang Z, Hu Q, Zhao J, Li C. Failure mode transformation of ZnO nanowires under uniaxial compression: from phase transition to buckling. NANOTECHNOLOGY 2019; 30:375702. [PMID: 31158830 DOI: 10.1088/1361-6528/ab269e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The failure modes of ZnO nanowires (NWs) with hexagonal cross section subjected to a uniaxial load are systematically investigated by using molecular dynamics (MD) simulations and two theoretical models considering the surface effect. Our results show that two different failure modes of the phase transition and buckling are triggered when the NWs are under uniaxial compression along the [0001] direction, in which the transformation between the two modes is related to the slenderness ratios of the NWs. Such slenderness-ratio-dependent mode transformation is mainly attributed to the competition between the critical stresses of phase transition and buckling. The Euler and Timoshenko models considering surface effect are further proposed to derive the critical slenderness for such mode transformation. The obtained analytical threshold values agree well with those of present MD simulations. Our results should be of great help for shedding some light on the design and application of functional devices based on ZnO NWs.
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Affiliation(s)
- Zhaowei Wang
- School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
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9
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Pan C, Zhai J, Wang ZL. Piezotronics and Piezo-phototronics of Third Generation Semiconductor Nanowires. Chem Rev 2019; 119:9303-9359. [PMID: 31364835 DOI: 10.1021/acs.chemrev.8b00599] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
With the fast development of nanoscience and nanotechnology in the last 30 years, semiconductor nanowires have been widely investigated in the areas of both electronics and optoelectronics. Among them, representatives of third generation semiconductors, such as ZnO and GaN, have relatively large spontaneous polarization along their longitudinal direction of the nanowires due to the asymmetric structure in their c-axis direction. Two-way or multiway couplings of piezoelectric, photoexcitation, and semiconductor properties have generated new research areas, such as piezotronics and piezo-phototronics. In this review, an in-depth discussion of the mechanisms and applications of nanowire-based piezotronics and piezo-phototronics is presented. Research on piezotronics and piezo-phototronics has drawn much attention since the effective manipulation of carrier transport, photoelectric properties, etc. through the application of simple mechanical stimuli and, conversely, since the design of new strain sensors based on the strain-induced change in semiconductor properties.
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Affiliation(s)
- Caofeng Pan
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems , Chinese Academy of Sciences , Beijing 100083 , P. R. China.,School of Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Junyi Zhai
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems , Chinese Academy of Sciences , Beijing 100083 , P. R. China.,School of Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Zhong Lin Wang
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems , Chinese Academy of Sciences , Beijing 100083 , P. R. China.,School of Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China.,School of Material Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
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10
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Conejeros S, Allan NL, Claeyssens F, Hart JN. Graphene and novel graphitic ZnO and ZnS nanofilms: the energy landscape, non-stoichiometry and water dissociation. NANOSCALE ADVANCES 2019; 1:1924-1935. [PMID: 36134212 PMCID: PMC9419858 DOI: 10.1039/c8na00155c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 03/22/2019] [Indexed: 06/16/2023]
Abstract
The energy landscapes of ultra-thin nanofilms of ZnO and ZnS are examined in detail using periodic hybrid density functional calculations. We predict new staggered graphitic forms, which are stable only for the thinnest films and are of particular interest as the electronic structure shows a spontaneous symmetry breaking across the film and consequently a marked decrease in band gap with thickness. The relative energies of the various forms, their structural and electronic properties and their variation with film thickness are discussed. Possible kinetic pathways for transitions from the graphitic forms are examined by explicit evaluation of transition state energies. For polar surfaces, such as (0001) würtzite and (111) zinc blende, many different mechanisms operate to remove or reduce the surface dipole depending on the number of layers in the nanofilm. The polar ZnS nanofilms, but not the polar ZnO analogues or any non-polar film, are predicted to spontaneously become non-stoichiometric by loss of zinc atoms from the surface. The behaviour of adsorbed water on the ultra-thin films is also examined. There is no dissociation on any ZnS film. For ZnO, dissociation into OH- and H+ takes place not only on (101̄0) würtzite, but also on (110) zinc blende. This result that does not appear to have been reported previously and deserves future experimental study. While we concentrate on ZnO and ZnS, similar energy landscapes are expected for any oxide or sulphide which adopts the würtzite or zinc blende structure in the bulk.
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Affiliation(s)
- Sergio Conejeros
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
- Departamento de Química, Universidad Católica del Norte Av. Angamos 0610 Antofagasta 1240000 Chile
| | - Neil L Allan
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Frederik Claeyssens
- University of Sheffield, Department of Materials Science and Engineering, Kroto Research Institute Broad Lane Sheffield S3 7HQ UK
| | - Judy N Hart
- School of Materials Science & Engineering, UNSW Sydney NSW 2052 Australia
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11
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First principles calculation of the nonhydrostatic effects on structure and Raman frequency of 3C-SiC. Sci Rep 2018; 8:11279. [PMID: 30050170 PMCID: PMC6062540 DOI: 10.1038/s41598-018-29666-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 07/09/2018] [Indexed: 11/29/2022] Open
Abstract
For understanding the quantitative effect of nonhydrostatic stress on properties of material, the crystal structure and Raman spectra of 3C-SiC under hydrostatic and nonhydrostatic stress were calculated using a first-principles method. The results show that the lattice constants (a, b, and c) under nonhydrostatic stresses deviate those under hydrostatic stress. The differences of the lattice constants under hydrostatic stress from nonhydrostatic stresses with differential stress were fitted by linear equation. Nonhydrostatic stress has no effect on density of 3C-SiC at high pressure, namely the equations of state of 3C-SiC under hydrostatic stress are same as those under nonhydrostatic stress. The frequencies and pressure dependences of LO and TO modes of 3C-SiC Raman spectra under nonhydrostatic stress are just same as those under hydrostatic stress. Under nonhydrostatic stress, there are four new lines with 361, 620, 740, and 803 cm−1 appeared in the Raman spectra except for the LO and TO lines because of the reduction of structure symmetry. However the frequencies and pressure dependences of the four Raman modes remain unchanged under different nonhydrostatic stresses. Appearance of new Raman modes under nonhydrostatic stress and the linear relationship of the differences of lattice constants under hydrostatic and nonhydrostatic stresses with differential stress can be used to indicate state of stress in high pressure experiments. The effect of nonhydrostatic stress on materials under high pressure is complicated and our calculation would help to understanding state of stress at high pressure experiments.
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12
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Tang Y, Chai H, Zhang H, Chen W, Zhang W, Dai X. Tuning the adsorption and interaction of CO and O 2 on graphene-like BC 3-supported non-noble metal atoms. Phys Chem Chem Phys 2018; 20:14040-14052. [PMID: 29745399 DOI: 10.1039/c8cp00772a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Research into suitable substrate-supported single-atom catalysts has become a major challenge for electrochemical sensors and energy devices. Firstly, we investigate the adsorption properties of metal atoms (MA = Fe, Co, Ni, Cu and Al) on pristine and defective BC3 sheets through using first-principles calculations. It is found that the MA-doped BC3 configurations (MA-BC3) are quite stable at high temperature and the positively charged MAs as surface active sites can effectively regulate the stability of reactive gases. Secondly, the adsorption of individual O2 molecules is more stable than that of CO molecules, which can modify the electronic and magnetic properties of MA-BC3 systems. Moreover, the possible reaction processes of CO oxidation on the Fe-BC3 substrate are comparably analyzed through the Eley-Rideal (ER) and Langmuir-Hinshelwood (LH) mechanisms. In the LH mechanism, the coadsorbed O2 and CO as starting materials start to form an OOCO complex with a smaller energy barrier (0.38 eV), which is an energetically more favorable process than that of the OOCO (0.65 eV) or CO3 complex (0.42 eV) formed through ER mechanisms. This result indicates that the functionalized MA-BC3 sheets have low cost and high activity.
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Affiliation(s)
- Yanan Tang
- Quantum Materials Research Center, College of Physics and Electronic Engineering, Zhengzhou Normal University, Zhengzhou 450044, China.
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13
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Tang Y, Zhang M, Shen Z, Zhou J, Chai H, Dai X. Non-metal atom anchored BC3 sheet: a promising low-cost and high-activity catalyst for CO oxidation. NEW J CHEM 2018. [DOI: 10.1039/c7nj04877g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Graphene-like BC3 monolayer as a new semiconducting nanomaterial has many unique properties.
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Affiliation(s)
- Yanan Tang
- Quantum Materials Research Center, College of Physics and Electronic Engineering, Zhengzhou Normal University
- Zhengzhou 450044
- China
| | - Minghui Zhang
- Quantum Materials Research Center, College of Physics and Electronic Engineering, Zhengzhou Normal University
- Zhengzhou 450044
- China
| | - Zigang Shen
- Quantum Materials Research Center, College of Physics and Electronic Engineering, Zhengzhou Normal University
- Zhengzhou 450044
- China
| | - Jincheng Zhou
- Quantum Materials Research Center, College of Physics and Electronic Engineering, Zhengzhou Normal University
- Zhengzhou 450044
- China
| | - Huadou Chai
- Quantum Materials Research Center, College of Physics and Electronic Engineering, Zhengzhou Normal University
- Zhengzhou 450044
- China
- College of Physics and Electronic Engineering, Henan Normal University
- Xinxiang
| | - Xianqi Dai
- Quantum Materials Research Center, College of Physics and Electronic Engineering, Zhengzhou Normal University
- Zhengzhou 450044
- China
- College of Physics and Electronic Engineering, Henan Normal University
- Xinxiang
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14
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Ayaz Khan S, Azam S, Kanoun MB, Murtaza G, Rani M, Goumri-Said S. Tailoring the electronic structure and optical properties of cadmium-doped zinc oxides nanosheet. ACTA ACUST UNITED AC 2017. [DOI: 10.1080/23311940.2017.1391734] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Saleem Ayaz Khan
- New Technologies–Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - Sikander Azam
- Department of Physics, The University of Lahore, Sargodha Campus, 40100 Pilsen, Pakistan
| | - Mohammed Benali Kanoun
- Department of Physics, College of Science, Alfaisal University, P.O. Box 50927, Riyadh 11533, Saudi Arabia
| | - Ghulam Murtaza
- Materials Modeling Lab, Department of Physics, Islamia College University, Peshawar, Pakistan
| | - Malika Rani
- Department of Physics, The Women University Multan, Multan, Pakistan
| | - Souraya Goumri-Said
- Department of Physics, College of Science, Alfaisal University, P.O. Box 50927, Riyadh 11533, Saudi Arabia
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15
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Viñes F, Lamiel-Garcia O, Illas F, Bromley ST. Size dependent structural and polymorphic transitions in ZnO: from nanocluster to bulk. NANOSCALE 2017; 9:10067-10074. [PMID: 28686276 DOI: 10.1039/c7nr02818k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We report on an extensive survey of (ZnO)N nanostructures ranging from bottom-up generated nanoclusters to top-down nanoparticles cuts from bulk polymorphs. The obtained results enable us to follow the energetic preferences of structure and polymorphism in (ZnO)N systems with N varying between 10-1026. This size range encompasses small nanoclusters with 10s of atoms and nanoparticles with 100s of atoms, which we also compare with appropriate bulk limits. In all cases the nanostructures and bulk systems are optimized using accurate all-electron, relativistic density functional theory based calculations with numeric atom centered orbital basis sets. Specifically, sets of five families of (ZnO)N species are considered: single-layered and multi-layered nanocages, and bulk cut nanoparticles from the sodalite (SOD), body centered tetragonal (BCT), and wurtzite (WZ) ZnO polymorphs. Using suitable fits to interpolate and extrapolate these data allows us to assess the size-dependent energetic stabilities of each family. With increasing size our results indicate a progressive change in energetic stability from single-layered to multi-layered cage-like nanoclusters. For nanoparticles of around 2.6 nm diameter we identify a transitional region where multi-layered cages, SOD, and BCT nanostructures are very similar in energetic stability. This transition size also marks the size regime at which bottom-up nanoclusters give way to top-down bulk-cut nanoparticles. Eventually, a final crossover is found where the most stable WZ-ZnO polymorph begins to energetically dominate at N ∼ 2200. This size corresponds to an approximate nanoparticle diameter of 4.7 nm, in line with experiments reporting the observation of wurtzite crystallinity in isolated ligand-free ZnO nanoparticles of 4-5 nm size or larger.
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Affiliation(s)
- Francesc Viñes
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1, 08028 Barcelona, Spain.
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16
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Wang J, Shen Y, Song F, Ke F, Liao X, Lu C. On the wurtzite to tetragonal phase transformation in ZnO nanowires. NANOTECHNOLOGY 2017; 28:165705. [PMID: 28273044 DOI: 10.1088/1361-6528/aa6566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
There is a long standing contradiction on the tensile response of zinc oxide nanowires between theoretical prediction and experimental observations. Although it is proposed that there is a ductile behavior dominated by phase transformation, only an elastic deformation and brittle fracture was witnessed in experiments. Using molecular dynamics simulations, we clarified that, as the lateral dimension of zinc oxide nanowires increases to a critical value, an unambiguous ductile-to-brittle transition occurs. The critical value increases with decreasing the strain rate. Factors including planar defects and surface contamination induce brittle fracture prior to the initiation of phase transformation. These findings are consistent with previous atomistic standpoints and experimental results.
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Affiliation(s)
- Jun Wang
- State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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17
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Zhang J. Phase transformation in two-dimensional crystalline silica under compressive loading. Phys Chem Chem Phys 2017; 19:8478-8484. [PMID: 28287227 DOI: 10.1039/c7cp00273d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using molecular dynamics simulations, we report a novel phase transformation from the hexagonal structure to the distorted structure in two-dimensional (2D) crystalline bilayer silica under uniaxial compression. In particular, the transformed distorted structures are found to be topographically different when the 2D silica is compressed in the zigzag and armchair directions, respectively. The compression-induced phase transformation has important implications for the physical responses of 2D silica. It is shown that the Young's modulus, Poisson's ratio and thermal conductivity of 2D silica are all greatly reduced after it transitions from the parent hexagonal phase to the transformed distorted phase. Moreover, we also find that the aforementioned material properties of 2D silica become strongly anisotropic after the phase transformation, in contrast to the isotropic material properties observed in the parent hexagonal phase of 2D silica.
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Affiliation(s)
- Jin Zhang
- Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055, China.
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18
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Attariani H, Momeni K, Adkins K. Defect Engineering: A Path toward Exceeding Perfection. ACS OMEGA 2017; 2:663-669. [PMID: 31457463 PMCID: PMC6641029 DOI: 10.1021/acsomega.6b00500] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 02/10/2017] [Indexed: 06/10/2023]
Abstract
Moving to nanoscale is a path to get perfect materials with superior properties. Yet defects, such as stacking faults (SFs), are still forming during the synthesis of nanomaterials and, according to common notion, degrade the properties. Here, we demonstrate the possibility of engineering defects to, surprisingly, achieve mechanical properties beyond those of the corresponding perfect structures. We show that introducing SFs with high density increases the Young's Modulus and the critical stress under compressive loading of the nanowires above those of a perfect structure. The physics can be explained by the increase in intrinsic strain due to the presence of SFs and overlapping of the corresponding strain fields. We have used the molecular dynamics technique and considered ZnO as our model material due to its technological importance for a wide range of electromechanical applications. The results are consistent with recent experiments and propose a novel approach for the fabrication of stronger materials.
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Affiliation(s)
- Hamed Attariani
- Department
of Mechanical and Materials Engineering, Wright State University, Dayton, Ohio 45435, United States
- Engineering
Program, Wright State University - Lake
Campus, Celina, Ohio 45822, United States
| | - Kasra Momeni
- Department
of Mechanical Engineering, Louisiana Tech
University, Ruston, Louisiana 71272, United States
| | - Kyle Adkins
- Department
of Mechanical and Materials Engineering, Wright State University, Dayton, Ohio 45435, United States
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19
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Wang H, Qin G, Li G, Wang Q, Hu M. Low thermal conductivity of monolayer ZnO and its anomalous temperature dependence. Phys Chem Chem Phys 2017; 19:12882-12889. [DOI: 10.1039/c7cp00460e] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The temperature dependent thermal conductivity of monolayer Zinc Oxide (ZnO) is found largely deviating from the traditional 1/T law.
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Affiliation(s)
- Huimin Wang
- Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education)
- Northeastern University
- 110819 Shenyang
- China
- Institute of Mineral Engineering
| | - Guangzhao Qin
- Institute of Mineral Engineering
- Division of Material Science and Engineering
- Faculty of Georesources and Materials Engineering
- RWTH Aachen University
- 52064 Aachen
| | - Guojian Li
- Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education)
- Northeastern University
- 110819 Shenyang
- China
| | - Qiang Wang
- Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education)
- Northeastern University
- 110819 Shenyang
- China
| | - Ming Hu
- Institute of Mineral Engineering
- Division of Material Science and Engineering
- Faculty of Georesources and Materials Engineering
- RWTH Aachen University
- 52064 Aachen
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20
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Yang S, Liu F, Wu C, Yang S. Tuning Surface Properties of Low Dimensional Materials via Strain Engineering. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:4028-4047. [PMID: 27376498 DOI: 10.1002/smll.201601203] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 05/26/2016] [Indexed: 06/06/2023]
Abstract
The promising and versatile applications of low dimensional materials are largely due to their surface properties, which along with their underlying electronic structures have been well studied. However, these materials may not be directly useful for applications requiring properties other than their natal ones. In recent years, strain has been shown to be an additionally useful handle to tune the physical and chemical properties of materials by changing their geometric and electronic structures. The strategies for producing strain are summarized. Then, the electronic structure of quasi-two dimensional layered non-metallic materials (e.g., graphene, MX2, BP, Ge nanosheets) under strain are discussed. Later, the strain effects on catalytic properties of metal-catalyst loaded with strain are focused on. Both experimental and computational perspectives for dealing with strained systems are covered. Finally, an outlook on engineering surface properties utilizing strain is provided.
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Affiliation(s)
- Shengchun Yang
- School of Science, MOE Key Laboratory for Non-Equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
- Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou Academy of Xi'an Jiaotong University, 215000, Suzhou, P. R. China
| | - Fuzhu Liu
- School of Science, MOE Key Laboratory for Non-Equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
- Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou Academy of Xi'an Jiaotong University, 215000, Suzhou, P. R. China
| | - Chao Wu
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, 710054, P. R. China
| | - Sen Yang
- School of Science, MOE Key Laboratory for Non-Equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
- Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou Academy of Xi'an Jiaotong University, 215000, Suzhou, P. R. China
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21
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Wang J, Zhang Y. Topologic connection between 2-D layered structures and 3-D diamond structures for conventional semiconductors. Sci Rep 2016; 6:24660. [PMID: 27090430 PMCID: PMC4835777 DOI: 10.1038/srep24660] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/29/2016] [Indexed: 11/25/2022] Open
Abstract
When coming to identify new 2D materials, our intuition would suggest us to look from layered instead of 3D materials. However, since graphite can be hypothetically derived from diamond by stretching it along its [111] axis, many 3D materials can also potentially be explored as new candidates for 2D materials. Using a density functional theory, we perform a systematic study over the common Group IV, III–V, and II–VI semiconductors along different deformation paths to reveal new structures that are topologically connected to but distinctly different from the 3D parent structure. Specifically, we explore two major phase transition paths, originating respectively from wurtzite and NiAs structure, by applying compressive and tensile strain along the symmetry axis, and calculating the total energy changes to search for potential metastable states, as well as phonon spectra to examine the structural stability. Each path is found to further split into two branches under tensile strain–low buckled and high buckled structures, which respectively lead to a low and high buckled monolayer structure. Most promising new layered or planar structures identified include BeO, GaN, and ZnO on the tensile strain side, Ge, Si, and GaP on the compressive strain side.
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Affiliation(s)
- Jianwei Wang
- Department of Electrical and Computer Engineering, The University of North Carolina at Charlotte 9201 University City Boulevard, Charlotte, NC 28223, USA.,Microsystem and Terahertz Research Center, China Academy of Engineering Physics 596 Yinhe Road, Shuangliu, Sichuang, 610200, China
| | - Yong Zhang
- Department of Electrical and Computer Engineering, The University of North Carolina at Charlotte 9201 University City Boulevard, Charlotte, NC 28223, USA
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22
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Shen J, Gong M, Dai Q, Ren S. Surface-Stress-Induced Phase Transformation of Ultrathin FeCo Nanowires. ACS APPLIED MATERIALS & INTERFACES 2016; 8:31-36. [PMID: 26709528 DOI: 10.1021/acsami.5b10991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ultrathin metal nanowires have attracted wide attention becau se oftheir unique anisotropy and surface-to-volume effects. In this study, we use ultrathin Au nanowires as the templating core to epitaxially grow magnetic iron-cobalt (FeCo) shell through metal-redox with the control on their thickness and stoichiometry. Large surface-stress-induced phase transformation in Au nanowires triggers and stabilizes metastable tetragonal FeCo nanostructure to enhance its magnetic anisotropy and coercivity. Meanwhile, under illumination, plasmon-induced hotspot in ultrathin Au nanowires enables the light-control on magnetic characteristics of FeCo shell. This study demonstrates the feasibility of surface-stress-induced phase transformation to stabilize and control metastable nanostructures for enhanced magnetic anisotropy, which is one of the key properties of functional magnetic materials.
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Affiliation(s)
- Jian Shen
- Department of Mechanical Engineering, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Maogang Gong
- Department of Mechanical Engineering, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Qilin Dai
- Department of Mechanical Engineering, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Shenqiang Ren
- Department of Mechanical Engineering, Temple University , Philadelphia, Pennsylvania 19122, United States
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23
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Watanabe K, Nagata T, Wakayama Y, Sekiguchi T, Erdélyi R, Volk J. Band-gap deformation potential and elasticity limit of semiconductor free-standing nanorods characterized in situ by scanning electron microscope-cathodoluminescence nanospectroscopy. ACS NANO 2015; 9:2989-3001. [PMID: 25689728 DOI: 10.1021/nn507159u] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Modern field-effect transistors or laser diodes take advantages of band-edge structures engineered by large uniaxial strain εzz, available up to an elasticity limit at a rate of band-gap deformation potential azz (= dEg/dεzz). However, contrary to aP values under hydrostatic pressure, there is no quantitative consensus on azz values under uniaxial tensile, compressive, and bending stress. This makes band-edge engineering inefficient. Here we propose SEM-cathodoluminescence nanospectroscopy under in situ nanomanipulation (Nanoprobe-CL). An apex of a c-axis-oriented free-standing ZnO nanorod (NR) is deflected by point-loading of bending stress, where local uniaxial strain (εcc = r/R) and its gradient across a NR (dεcc/dr = R(-1)) are controlled by a NR local curvature (R(-1)). The NR elasticity limit is evaluated sequentially (εcc = 0.04) from SEM observation of a NR bending deformation cycle. An electron beam is focused on several spots crossing a bent NR, and at each spot the local Eg is evaluated from near-band-edge CL emission energy. Uniaxial acc (= dEg/dεcc) is evaluated at regulated surface depth, and the impact of R(-1) on observed acc is investigated. The acc converges with -1.7 eV to the R(-1) = 0 limit, whereas it quenches with increasing R(-1), which is attributed to free-exciton drift under transversal band-gap gradient. Surface-sensitive CL measurements suggest that a discrepancy from bulk acc = -4 eV may originate from strain relaxation at the side surface under uniaxial stress. The nanoprobe-CL technique reveals an Eg(εij) response to specific strain tensor εij (i, j = x, y, z) and strain-gradient effects on a minority carrier population, enabling simulations and strain-dependent measurements of nanodevices with various structures.
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Affiliation(s)
- Kentaro Watanabe
- †WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- ‡Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan
| | - Takahiro Nagata
- †WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Yutaka Wakayama
- †WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Sekiguchi
- †WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Róbert Erdélyi
- §MTA EK Institute of Technical Physics and Materials Science, Konkoly Thege M. út 29-33, 1121 Budapest, Hungary
| | - János Volk
- §MTA EK Institute of Technical Physics and Materials Science, Konkoly Thege M. út 29-33, 1121 Budapest, Hungary
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24
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Shrama SK, Saurakhiya N, Barthwal S, Kumar R, Sharma A. Tuning of structural, optical, and magnetic properties of ultrathin and thin ZnO nanowire arrays for nano device applications. NANOSCALE RESEARCH LETTERS 2014; 9:122. [PMID: 24636275 PMCID: PMC4003861 DOI: 10.1186/1556-276x-9-122] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 02/19/2014] [Indexed: 05/26/2023]
Abstract
One-dimensional (1-D) ultrathin (15 nm) and thin (100 nm) aligned 1-D (0001) and (0001¯) oriented zinc oxide (ZnO) nanowire (NW) arrays were fabricated on copper substrates by one-step electrochemical deposition inside the pores of polycarbonate membranes. The aspect ratio dependence of the compressive stress because of the lattice mismatch between NW array/substrate interface and crystallite size variations is investigated. X-ray diffraction results show that the polycrystalline ZnO NWs have a wurtzite structure with a = 3.24 Å, c = 5.20 Å, and [002] elongation. HRTEM and SAED pattern confirmed the polycrystalline nature of ultrathin ZnO NWs and lattice spacing of 0.58 nm. The crystallite size and compressive stress in as-grown 15- and 100-nm wires are 12.8 nm and 0.2248 GPa and 22.8 nm and 0.1359 GPa, which changed to 16.1 nm and 1.0307 GPa and 47.5 nm and 1.1677 GPa after annealing at 873 K in ultrahigh vacuum (UHV), respectively. Micro-Raman spectroscopy showed that the increase in E2 (high) phonon frequency corresponds to much higher compressive stresses in ultrathin NW arrays. The minimum-maximum magnetization magnitude for the as-grown ultrathin and thin NW arrays are approximately 8.45 × 10-3 to 8.10 × 10-3 emu/g and approximately 2.22 × 10-7 to 2.190 × 10-7 emu/g, respectively. The magnetization in 15-nm NW arrays is about 4 orders of magnitude higher than that in the 100 nm arrays but can be reduced greatly by the UHV annealing. The origin of ultrathin and thin NW array ferromagnetism may be the exchange interactions between localized electron spin moments resulting from oxygen vacancies at the surfaces of ZnO NWs. The n-type conductivity of 15-nm NW array is higher by about a factor of 2 compared to that of the 100-nm ZnO NWs, and both can be greatly enhanced by UHV annealing. The ability to tune the stresses and the structural and relative occupancies of ZnO NWs in a wide range by annealing has important implications for the design of advanced photonic, electronic, and magneto-optic nano devices.
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Affiliation(s)
- Satinder K Shrama
- School of Computing and Electrical Engineering, Indian Institute of Technology (IIT)-Mandi, Mandi, Himanchal Pradesh 175001, India
- DST Unit on Nanosciences, Department of Chemical Engineering, Indian Institute of Technology (IIT)-Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Neelam Saurakhiya
- DST Unit on Nanosciences, Department of Chemical Engineering, Indian Institute of Technology (IIT)-Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Sumit Barthwal
- DST Unit on Nanosciences, Department of Chemical Engineering, Indian Institute of Technology (IIT)-Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Rudra Kumar
- DST Unit on Nanosciences, Department of Chemical Engineering, Indian Institute of Technology (IIT)-Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Ashutosh Sharma
- DST Unit on Nanosciences, Department of Chemical Engineering, Indian Institute of Technology (IIT)-Kanpur, Kanpur, Uttar Pradesh 208016, India
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25
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Momeni K, Attariani H. Electromechanical properties of 1D ZnO nanostructures: nanopiezotronics building blocks, surface and size-scale effects. Phys Chem Chem Phys 2014; 16:4522-7. [PMID: 24296508 DOI: 10.1039/c3cp54456g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
One-dimensional (1D) zinc oxide nanostructures are the main components of nanogenerators and central to the emerging field of nanopiezotronics. Understanding the underlying physics and quantifying the electromechanical properties of these structures, the topic of this research study, play a major role in designing next-generation nanoelectromechanical devices. Here, atomistic simulations are utilized to study surface and size-scale effects on the electromechanical response of 1D ZnO nanostructures. It is shown that the mechanical and piezoelectric properties of these structures are controlled by their size, cross-sectional geometry, and loading configuration. The study reveals enhancement of the piezoelectric and elastic modulus of ZnO nanowires (NW) with diameter d > 1 nm, followed by a sudden drop for d < 1 nm due to transformation of NWs to nanotubes (NTs). Degradation of mechanical and piezoelectric properties of ZnO nanobelts (NBs) followed by an enhancement in piezoelectric properties occurs when their lower dimension is reduced to <1 nm. The latter enhancement can be explained in the context of surface reconfiguration and formation of hexagon-tetragon (HT) pairs at the intersection of (21[combining macron]1[combining macron]0) and (011[combining macron]0) planes in NBs. Transition from a surface-reconstructed dominant to a surface-relaxed dominant region is demonstrated for lateral dimensions <1 nm. New phase-transformation (PT) kinetics from piezoelectric wurtzite to nonpiezoelectric body-centered tetragonal (WZ → BCT) and graphite-like phase (WZ → HX) structures occurs in ZnO NWs loaded up to large strains of ∼10%.
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Affiliation(s)
- Kasra Momeni
- Department of Aerospace Engineering, Iowa State University, Ames, Iowa 50011, USA.
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26
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Jiang JW, Park HS, Rabczuk T. Polar surface effects on the thermal conductivity of ZnO nanowires: a shell-like surface reconstruction-induced preserving mechanism. NANOSCALE 2013; 5:11035-11043. [PMID: 24071784 DOI: 10.1039/c3nr03567k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We perform molecular dynamics (MD) simulations to investigate the effect of polar surfaces on the thermal transport in zinc oxide (ZnO) nanowires. We find that the thermal conductivity of nanowires with free polar (0001) surfaces is much higher than that of nanowires that have been stabilized with reduced charges on the polar (0001) surfaces, and also hexagonal nanowires without any transverse polar surface, where the reduced charge model has been proposed as a promising stabilization mechanism for the (0001) polar surfaces of ZnO nanowires. From normal mode analysis, we show that the higher thermal conductivity is due to the shell-like reconstruction that occurs for the free polar surfaces. This shell-like reconstruction suppresses twisting motion in the nanowires such that the bending phonon modes are not scattered by the other phonon modes, and this leads to substantially higher thermal conductivity of the ZnO nanowires with free polar surfaces. Furthermore, the auto-correlation function of the normal mode coordinate is utilized to extract the phonon lifetime, which leads to a concise explanation for the higher thermal conductivity of ZnO nanowires with free polar surfaces. Our work demonstrates that ZnO nanowires without polar surfaces, which exhibit low thermal conductivity, are more promising candidates for thermoelectric applications than nanowires with polar surfaces (and also high thermal conductivity).
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Affiliation(s)
- Jin-Wu Jiang
- Shanghai Institute of Applied Mathematics and Mechanics, Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai University, Shanghai 200072, People's Republic of China.
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27
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Jiang JW, Park HS, Rabczuk T. Preserving the Q-factors of ZnO nanoresonators via polar surface reconstruction. NANOTECHNOLOGY 2013; 24:405705. [PMID: 24029380 DOI: 10.1088/0957-4484/24/40/405705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We perform molecular dynamics simulations to investigate the effect of polar surfaces on the quality (Q)-factors of zinc oxide (ZnO) nanowire-based nanoresonators. We find that the Q-factors in ZnO nanoresonators with free polar (0001) surfaces are about one order of magnitude higher than in nanoresonators that have been stabilized with reduced charges on the polar (0001) surfaces. From normal mode analysis, we show that the higher Q-factor is due to a shell-like reconstruction that occurs for the free polar surfaces. This shell-like reconstruction suppresses twisting motion in the nanowires such that the mixing of other modes with the resonant mode of oscillation is minimized, and leads to substantially higher Q-factors in ZnO nanoresonators with free polar surfaces.
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Affiliation(s)
- Jin-Wu Jiang
- Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstraße 15, D-99423 Weimar, Germany
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28
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Demiroglu I, Bromley ST. Nanofilm versus bulk polymorphism in Wurtzite materials. PHYSICAL REVIEW LETTERS 2013; 110:245501. [PMID: 25165935 DOI: 10.1103/physrevlett.110.245501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Indexed: 06/03/2023]
Abstract
We generate a wide range of hexagonal sheet-based ZnO polymorphs inspired by enumeration of their characteristic underlying nets. Evaluating the bulk and nanofilm stabilities of these structures with ab initio calculations allows for an unprecedented overview of (nano)polymorphism in wurtzite materials. We find a rich low energy nanofilm polymorphism with a totally distinct stability ordering to that in the bulk. From this general basis we provide new insights into structural transitions observed during epitaxial growth and predictions for nanofilm stability with varying strain or thickness.
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Affiliation(s)
- Ilker Demiroglu
- Departament de Química Física and Institut de Química Teòrica i Computacional, Universitat de Barcelona, E-08028 Barcelona, Spain
| | - Stefan T Bromley
- Departament de Química Física and Institut de Química Teòrica i Computacional, Universitat de Barcelona, E-08028 Barcelona, Spain and Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
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29
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Affiliation(s)
- Min Zhou
- School of Mechanical Engineering and School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA, and World Class University (WCU) Program on Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744, Korea
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30
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Espinosa HD, Bernal RA, Minary-Jolandan M. A review of mechanical and electromechanical properties of piezoelectric nanowires. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:4656-4675. [PMID: 22581695 DOI: 10.1002/adma.201104810] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Indexed: 05/31/2023]
Abstract
Piezoelectric nanowires are promising building blocks in nanoelectronic, sensing, actuation and nanogenerator systems. In spite of great progress in synthesis methods, quantitative mechanical and electromechanical characterization of these nanostructures is still limited. In this article, the state-of-the art in experimental and computational studies of mechanical and electromechanical properties of piezoelectric nanowires is reviewed with an emphasis on size effects. The review covers existing characterization and analysis methods and summarizes data reported in the literature. It also provides an assessment of research needs and opportunities. Throughout the discussion, the importance of coupling experimental and computational studies is highlighted. This is crucial for obtaining unambiguous size effects of nanowire properties, which truly reflect the effect of scaling rather than a particular synthesis route. We show that such a combined approach is critical to establish synthesis-structure-property relations that will pave the way for optimal usage of piezoelectric nanowires.
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Affiliation(s)
- Horacio D Espinosa
- Department of Mechanical Engineering, Northwestern University, Evanston, IL60208-3111, USA.
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32
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He MR, Yu R, Zhu J. Reversible wurtzite-tetragonal reconstruction in ZnO(1010) surfaces. Angew Chem Int Ed Engl 2012; 51:7744-7. [PMID: 22730148 DOI: 10.1002/anie.201202598] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 05/21/2012] [Indexed: 11/11/2022]
Abstract
Bistable surface: The reversible phase transition between wurtzite (WZ) and body-centered-tetragonal (BCT) lattice was activated in ZnO(1010) surfaces and directly imaged at atomic scale by using aberration-corrected electron microscopy. A nucleation-growth mechanism for the surface reconstruction is further proposed based on observations and calculations of the WZ-BCT domain boundary.
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Affiliation(s)
- Mo-Rigen He
- Beijing National Center for Electron Microscopy, Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
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33
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He MR, Yu R, Zhu J. Reversible Wurtzite-Tetragonal Reconstruction in ZnO(10$\bar 1$0) Surfaces. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202598] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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34
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Study of effect of water vapor and mechanical strain on thermal conductivity of zinc oxide using the ReaxFF reactive force field. COMPUT THEOR CHEM 2012. [DOI: 10.1016/j.comptc.2012.02.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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Hapiuk D, Marques MAL, Melinon P, Flores-Livas JA, Botti S, Masenelli B. p doping in expanded phases of ZnO: an ab initio study. PHYSICAL REVIEW LETTERS 2012; 108:115903. [PMID: 22540489 DOI: 10.1103/physrevlett.108.115903] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 11/21/2011] [Indexed: 05/31/2023]
Abstract
The issue of p doping in nanostructured cagelike ZnO is investigated by state-of-the-art calculations. Our study is focused on one prototypical structure, namely, sodalite, for which we show that p-type doping is possible for elements of the V, VI, and VII columns of the periodic table. However, some dopants tend to form dimers, thus impairing the stability of this kind of doping. This difference of behavior is discussed, and two criteria are proposed to ensure stable p doping.
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Affiliation(s)
- D Hapiuk
- Université de Lyon, F-69000 Lyon, France.
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Melis C, Raiteri P, Colombo L, Mattoni A. Self-assembling of zinc phthalocyanines on ZnO (1010) surface through multiple time scales. ACS NANO 2011; 5:9639-9647. [PMID: 22047169 DOI: 10.1021/nn203105w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We adopt a hierarchic combination of theoretical methods to study the assembling of zinc phthalocyanines (ZnPcs) on a ZnO (1010) surface through multiple time scales. Atomistic simulations, such as model potential molecular dynamics and metadynamics, are used to study the energetics and short time evolution (up to ∼100 ns) of small ZnPc aggregates. The stability and the lifetime of large clusters is then studied by means of an atomistically informed coarse-grained model using classical molecular dynamics. Finally, the macroscopic time scale clustering phenomenon is studied by Metropolis Monte Carlo algorithms as a function of temperature and surface coverage. We provide evidence that at room temperature the aggregation is likely to occur at sufficiently high coverage, and we characterize the nature, morphology, and lifetime of ZnPc's clusters. We identify the molecular stripes oriented along [010] crystallographic directions as the most energetically stable aggregates.
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Affiliation(s)
- Claudio Melis
- Dipartimento di Fisica, Università di Cagliari, I-09042 Monserrato (Ca), Italy.
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Wu JY, Nagao S, He JY, Zhang ZL. Role of five-fold twin boundary on the enhanced mechanical properties of fcc Fe nanowires. NANO LETTERS 2011; 11:5264-5273. [PMID: 22050778 DOI: 10.1021/nl202714n] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The role of 5-fold twin boundary on the structural and mechanical properties of fcc Fe nanowire under tension is explored by classical molecular dynamics. Twin-stabilized fcc nanowire with various diameters (6-24 nm) are examined by tension tests at several temperatures ranging from 0.01 to 1100 K. Significant increase in the Young's modulus of the smaller nanowires is revealed to originate from the central area of quinquefoliolate-like stress-distribution over the 5-fold twin, rather than from the surface tension that is often considered as the main source of such size-effects found in nanostructures. Because of the excess compressive stress caused by crossing twin-boundaries, the atoms in the center behave stiffer than those in bulk and even expand laterally under axial tension, providing locally negative Poisson's ratio. The yield strength of nanowire is also enhanced by the twin boundary that suppresses dislocation nucleation within a fcc twin-domain; therefore, the plasticity of nanowire is initiated by strain-induced fcc→bcc phase transformation that destroys the twin structure. After the yield, the nucleated bcc phase immediately spreads to the entire area, and forms a multigrain structure to realize ductile deformation followed by necking. As temperature elevated close to the critical temperature between bcc and fcc phases, the increased stability of fcc phase competes with the phase transformation under tension, and hence dislocation nucleations in fcc phase are observed exclusively at the highest temperature in our study.
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Affiliation(s)
- J Y Wu
- NTNU Nanomechanical Lab, Norwegian University of Science and Technology (NTNU), Trondheim N-7491, Norway
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38
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Guo HX, Fujita D. Developments of scanning probe microscopy with stress/strain fields. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2011; 82:123706. [PMID: 22225223 DOI: 10.1063/1.3669526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
An innovative stress/strain fields scanning probe microscopy in ultra high vacuum (UHV) environments is developed for the first time. This system includes scanning tunneling microscope (STM) and noncontact atomic force microscope (NC-AFM). Two piezo-resistive AFM cantilever probes and STM probes used in this system can move freely in XYZ directions. The nonoptical frequency shift detection of the AFM probe makes the system compact enough to be set in the UHV chambers. The samples can be bent by an anvil driven by a step motor to induce stress and strain on their surface. With a direct current (dc) power source, the sample can be observed at room and high temperatures. A long focus microscope and a monitor are used to observe the samples and the operation of STM and AFM. Silicon(111) surface in room temperature and silicon(001) surface in high temperature with stress were investigated to check the performance of the scanning probe microscope.
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Affiliation(s)
- H X Guo
- International Center for Materials Nano-architectonics (MANA), National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
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Demchenko DO, Heinz PD, Lee B. Determining factors of thermoelectric properties of semiconductor nanowires. NANOSCALE RESEARCH LETTERS 2011; 6:502. [PMID: 21854613 PMCID: PMC3212017 DOI: 10.1186/1556-276x-6-502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 08/19/2011] [Indexed: 05/31/2023]
Abstract
It is widely accepted that low dimensionality of semiconductor heterostructures and nanostructures can significantly improve their thermoelectric efficiency. However, what is less well understood is the precise role of electronic and lattice transport coefficients in the improvement. We differentiate and analyze the electronic and lattice contributions to the enhancement by using a nearly parameter-free theory of the thermoelectric properties of semiconductor nanowires. By combining molecular dynamics, density functional theory, and Boltzmann transport theory methods, we provide a complete picture for the competing factors of thermoelectric figure of merit. As an example, we study the thermoelectric properties of ZnO and Si nanowires. We find that the figure of merit can be increased as much as 30 times in 8-Å-diameter ZnO nanowires and 20 times in 12-Å-diameter Si nanowires, compared with the bulk. Decoupling of thermoelectric contributions reveals that the reduction of lattice thermal conductivity is the predominant factor in the improvement of thermoelectric properties in nanowires. While the lattice contribution to the efficiency enhancement consistently becomes larger with decreasing size of nanowires, the electronic contribution is relatively small in ZnO and disadvantageous in Si.
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Affiliation(s)
- Denis O Demchenko
- Department of Physics, Virginia Commonwealth University, Richmond, VA 23284, USA
| | - Peter D Heinz
- Department of Physics, Texas State University, San Marcos, TX 78666, USA
| | - Byounghak Lee
- Department of Physics, Texas State University, San Marcos, TX 78666, USA
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40
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Lee WJ, Chang JG, Ju SP, Weng MH, Lee CH. Structure-dependent mechanical properties of ultrathin zinc oxide nanowires. NANOSCALE RESEARCH LETTERS 2011; 6:352. [PMID: 21711876 PMCID: PMC3211442 DOI: 10.1186/1556-276x-6-352] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 04/20/2011] [Indexed: 05/31/2023]
Abstract
Mechanical properties of ultrathin zinc oxide (ZnO) nanowires of about 0.7-1.1 nm width and in the unbuckled wurtzite (WZ) phase have been carried out by molecular dynamics simulation. As the width of the nanowire decreases, Young's modulus, stress-strain behavior, and yielding stress all increase. In addition, the yielding strength and Young's modulus of Type III are much lower than the other two types, because Type I and II have prominent edges on the cross-section of the nanowire. Due to the flexibility of the Zn-O bond, the phase transformation from an unbuckled WZ phase to a buckled WZ is observed under the tensile process, and this behavior is reversible. Moreover, one- and two-atom-wide chains can be observed before the ZnO nanowires rupture. These results indicate that the ultrathin nanowire possesses very high malleability.
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Affiliation(s)
- Wen-Jay Lee
- National Center for High-Performance Computing, No. 28, Nan-Ke Third Road, Hsin-Shi, Tainan 74147, Taiwan
| | - Jee-Gong Chang
- National Center for High-Performance Computing, No. 28, Nan-Ke Third Road, Hsin-Shi, Tainan 74147, Taiwan
| | - Shin-Pon Ju
- Department of Mechanical and Electro-Mechanical Engineering, Center for Nanoscience and Nanotechnology, National Sun Yat-sen University Kaohsiung, 804, Taiwan
| | - Meng-Hsiung Weng
- Department of Mechanical and Electro-Mechanical Engineering, Center for Nanoscience and Nanotechnology, National Sun Yat-sen University Kaohsiung, 804, Taiwan
| | - Chia-Hung Lee
- Department of Mechanical and Electro-Mechanical Engineering, Center for Nanoscience and Nanotechnology, National Sun Yat-sen University Kaohsiung, 804, Taiwan
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41
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Sayle TXT, Inkson BJ, Karakoti A, Kumar A, Molinari M, Möbus G, Parker SC, Seal S, Sayle DC. Mechanical properties of ceria nanorods and nanochains; the effect of dislocations, grain-boundaries and oriented attachment. NANOSCALE 2011; 3:1823-1837. [PMID: 21409243 DOI: 10.1039/c0nr00980f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We predict that the presence of extended defects can reduce the mechanical strength of a ceria nanorod by 70%. Conversely, the pristine material can deform near its theoretical strength limit. Specifically, atomistic models of ceria nanorods have been generated with full microstructure, including: growth direction, morphology, surface roughening (steps, edges, corners), point defects, dislocations and grain-boundaries. The models were then used to calculate the mechanical strength as a function of microstructure. Our simulations reveal that the compressive yield strengths of ceria nanorods, ca. 10 nm in diameter and without extended defects, are 46 and 36 GPa for rods oriented along [211] and [110] respectively, which represents almost 10% of the bulk elastic modulus and are associated with yield strains of about 0.09. Tensile yield strengths were calculated to be about 50% lower with associated yield strains of about 0.06. For both nanorods, plastic deformation was found to proceed via slip in the {001} plane with direction <110>--a primary slip system for crystals with the fluorite structure. Dislocation evolution for the nanorod oriented along [110] was nucleated via a cerium vacancy present at the surface. A nanorod oriented along [321] and comprising twin-grain boundaries with {111} interfacial planes was calculated to have a yield strength of about 10 GPa (compression and tension) with the grain boundary providing the vehicle for plastic deformation, which slipped in the plane of the grain boundary, with an associated <110> slip direction. We also predict, using a combination of atomistic simulation and DFT, that rutile-structured ceria is feasible when the crystal is placed under tension. The mechanical properties of nanochains, comprising individual ceria nanoparticles with oriented attachment and generated using simulated self-assembly, were found to be similar to those of the nanorod with grain-boundary. Images of the atom positions during tension and compression are shown, together with animations, revealing the mechanisms underpinning plastic deformation. For the nanochain, our simulations help further our understanding of how a crystallising ice front can be used to 'sculpt' ceria nanoparticles into nanorods via oriented attachment.
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Affiliation(s)
- Thi X T Sayle
- Dept. Engineering and Applied Science, Cranfield University, Defence Academy of the United Kingdom, Shrivenham, SN6 8LA, UK.
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43
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Dai S, Dunn ML, Park HS. Piezoelectric constants for ZnO calculated using classical polarizable core-shell potentials. NANOTECHNOLOGY 2010; 21:445707. [PMID: 20935348 DOI: 10.1088/0957-4484/21/44/445707] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We demonstrate the feasibility of using classical atomistic simulations, i.e. molecular dynamics and molecular statics, to study the piezoelectric properties of ZnO using core-shell interatomic potentials. We accomplish this by reporting the piezoelectric constants for ZnO as calculated using two different classical interatomic core-shell potentials: that originally proposed by Binks and Grimes (1994 Solid State Commun. 89 921-4), and that proposed by Nyberg et al (1996 J. Phys. Chem. 100 9054-63). We demonstrate that the classical core-shell potentials are able to qualitatively reproduce the piezoelectric constants as compared to benchmark ab initio calculations. We further demonstrate that while the presence of the shell is required to capture the electron polarization effects that control the clamped ion part of the piezoelectric constant, the major shortcoming of the classical potentials is a significant underprediction of the clamped ion term as compared to previous ab initio results. However, the present results suggest that overall, these classical core-shell potentials are sufficiently accurate to be utilized for large scale atomistic simulations of the piezoelectric response of ZnO nanostructures.
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Affiliation(s)
- Shuangxing Dai
- Department of Mechanical Engineering, University of Colorado, Boulder, CO 80309, USA
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44
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Horlait D, Coasne B, Mezy A, Ravot D, Tedenac JC. Molecular simulation of zinc oxide nanostructures confined in carbon nanotubes. MOLECULAR SIMULATION 2010. [DOI: 10.1080/08927022.2010.501798] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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45
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Tang Q, Li Y, Zhou Z, Chen Y, Chen Z. Tuning electronic and magnetic properties of wurtzite ZnO nanosheets by surface hydrogenation. ACS APPLIED MATERIALS & INTERFACES 2010; 2:2442-2447. [PMID: 20695444 DOI: 10.1021/am100467j] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Through density functional theory computations, we systematically investigated the structural, electronic, and magnetic properties as well as the relative stabilities of fully and partially hydrogenated ZnO nanosheets. Unlike bare ZnO nanosheets terminating with polar {0001} surfaces, their hydrogenated counterparts preserve the initial wurtzite configuration. Full hydrogenation is more favorable energetically for thinner ZnO nanosheets, whereas semihydrogenation at O sites is preferred for thicker ones. Moreover, semiconductor --> half-metal --> metal transition occurs with nonmagnetic --> magnetic transfer upon adopting surface hydrogenation and increasing sheet thickness. The predicted diverse and tunable electronic and magnetic properties endow ZnO nanosheets potential applications in electronics and spintronics.
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Affiliation(s)
- Qing Tang
- Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry, Ministry of Education, Nankai University, Tianjin 300071, P. R. China
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Stradi D, Illas F, Bromley ST. Prospective role of multicenter bonding for efficient and selective hydrogen transport. PHYSICAL REVIEW LETTERS 2010; 105:045901. [PMID: 20867863 DOI: 10.1103/physrevlett.105.045901] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 05/19/2010] [Indexed: 05/29/2023]
Abstract
Multicenter bonding is shown to be able to dramatically reduce atomic transport barriers in solids. Theoretical analysis of H atoms in a nanoporous polymorph of ZnO (SOD-ZnO) shows intercage hopping to be aided by four-center bonds which: (i) radically reduce the sterically hindered H-transport barrier to be close to that found in Pd membranes, and (ii) induce p doping. SOD-ZnO is also shown to be thermodynamically favored under triaxial tension and selective for encapsulating weakly perturbed H atoms. Such materials have potential use in atomic transport, control, and purification.
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Affiliation(s)
- Daniele Stradi
- Department de Química Física & Institut de Química Teórica i Computacional (IQTCUB), Universitat de Barcelona, E-08028 Barcelona, Spain
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47
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Sangthong W, Limtrakul J, Illas F, Bromley ST. Persistence of magic cluster stability in ultra-thin semiconductor nanorods. NANOSCALE 2010; 2:72-77. [PMID: 20648366 DOI: 10.1039/b9nr00282k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The progression from quasi zero-dimensional (Q0D) nanoclusters to quasi one-dimensional (Q1D) nanorods, and, with increasing length, to nanowires, represents the most conceptually fundamental transition from the nanoscale to bulk-like length scales. This dimensionality crossover is particularly interesting, both scientifically and technologically, for inorganic semiconducting (ISC) materials, where striking concomitant changes in optoelectronic properties occur.(1,2) Such effects are most pronounced for ultra-thin(3) ISC nanorods/nanowires, where the confining and defective nature of the atomic structure become key. Although experiments on ISC materials in this size regime have revealed especially stable (or "magic") non-bulk-like Q0D nanoclusters,(4,5) all ISC Q1D nanostructures have been reported as having structures corresponding to bulk crystalline phases. For two important ISC materials (CdS and CdSe) we track the Q0D-to-Q1D transition employing state-of-the-art electronic structure calculations demonstrating an unexpected persistence of magic cluster stability over the bulk-like structure in ultra-thin nanorods up to >10 nm in length. The transition between the magic-cluster-based and wurtzite nanorods is found to be accompanied by a large change in aspect ratio thus potentially providing a route to nano-mechanical transducer applications.
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Affiliation(s)
- Winyoo Sangthong
- Departament de Química Física & Institut de Química Teòrica i Computacional, Universitat de Barcelona, C/Martí i Franquès 1, Barcelona, Spain
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Sangthong W, Limtrakul J, Illas F, Bromley ST. Predicting transition pressures for obtaining nanoporous semiconductor polymorphs: oxides and chalcogenides of Zn, Cd and Mg. Phys Chem Chem Phys 2010; 12:8513-20. [DOI: 10.1039/c0cp00002g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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49
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Xu LZ, Liu YL, Zhou HB, Liu LH, Zhang Y, Lu GH. Ideal strengths, structure transitions, and bonding properties of a ZnO single crystal under tension. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:495402. [PMID: 21836196 DOI: 10.1088/0953-8984/21/49/495402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We perform a first-principles computational tensile test (FPCTT) on a ZnO single crystal based on density functional theory to systematically investigate structural transitions, mechanical, and intrinsic bonding properties in the three representative directions, [Formula: see text], [0001], and [Formula: see text]. Stress as a function of tensile strain shows that the ideal tensile strengths in the three directions are 16.2 GPa, 22.4 GPa, and 19.0 GPa, corresponding to strains of 0.20, 0.16, and 0.16, respectively. The [0001] is the strongest direction due to the strongest bonding between the most closely packed Zn and O(0001) layers. We demonstrate that different structures in these three directions lead to different structural transitions, i.e. from a wurtzite (WZ) to a body-centered tetragonal (BCT) structure for [Formula: see text], to a graphite-like (GP-like) structure for [0001], and to a quasi-hexagonal (quasi-HX) structure for [Formula: see text], respectively. Bond length and charge density evolution under tension indicate the occurrence of bond formation and disassociation during these structure transitions. New O-Zn bonds form in the WZ [Formula: see text] BCT and WZ [Formula: see text] quasi-HX transitions, and the original O-Zn bonds break in the WZ [Formula: see text] GP-like transition.
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Affiliation(s)
- Li-Zhi Xu
- Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100191, People's Republic of China
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50
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Schmidt TM, Miwa RH. An ab initio study of energetic stability and electronic confinement for different structural phases of ZnO nanowires. NANOTECHNOLOGY 2009; 20:215202. [PMID: 19423926 DOI: 10.1088/0957-4484/20/21/215202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We performed an ab initio total energy investigation of hexagonal (wurtzite and graphitic) and zinc blende ZnO nanowires (NWs) aligned along the [0001] and [111] directions, respectively, as a function of the NW diameter. We have considered unpassivated and (hydrogen) passivated NW surfaces. For the unpassivated system, we find that the wurtzite phase represents the energetically most favorable configuration. The width of the energy bandgap of wurtzite ZnO NWs increases by reducing the NW diameter, which is in accordance with the one-dimensional confinement effect. In contrast, this property fails in the zinc blende and graphitic NWs. In the former it is due to the high density of surface states within the fundamental bandgap, while in the latter system the energy bandgap becomes indirect and increases slowly by reducing the NW diameter. Our total energy results indicate that the hydrogen-passivated ZnO NWs are more stable than the unpassivated ones. For thin hydrogen-passivated NWs, we find that the graphitic phase becomes more stable than the wurtzite. For NW diameters around 2 nm, the graphitic and wurtzite phases present similar formation energies, while for larger diameters the wurtzite NWs become energetically more favorable. Finally, comparing the behavior and the positions of the valence and conduction band edges for the unpassivated ZnO NWs, we proposed the formation of type II band alignment for a hypothetical wurtzite/graphitic NW heterojunction.
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Affiliation(s)
- T M Schmidt
- Instituto de Física, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
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