1
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Wang H, Zhang J, Shen C, Yang C, Küster K, Deuschle J, Starke U, Zhang H, Isobe M, Huang D, van Aken PA, Takagi H. Direct visualization of stacking-selective self-intercalation in epitaxial Nb 1+xSe 2 films. Nat Commun 2024; 15:2541. [PMID: 38514672 PMCID: PMC10957900 DOI: 10.1038/s41467-024-46934-0] [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: 10/19/2023] [Accepted: 03/14/2024] [Indexed: 03/23/2024] Open
Abstract
Two-dimensional (2D) van der Waals (vdW) materials offer rich tuning opportunities generated by different stacking configurations or by introducing intercalants into the vdW gaps. Current knowledge of the interplay between stacking polytypes and intercalation often relies on macroscopically averaged probes, which fail to pinpoint the exact atomic position and chemical state of the intercalants in real space. Here, by using atomic-resolution electron energy-loss spectroscopy in a scanning transmission electron microscope, we visualize a stacking-selective self-intercalation phenomenon in thin films of the transition-metal dichalcogenide (TMDC) Nb1+xSe2. We observe robust contrasts between 180°-stacked layers with large amounts of Nb intercalants inside their vdW gaps and 0°-stacked layers with little detectable intercalants inside their vdW gaps, coexisting on the atomic scale. First-principles calculations suggest that the films lie at the boundary of a phase transition from 0° to 180° stacking when the intercalant concentration x exceeds ~0.25, which we could attain in our films due to specific kinetic pathways. Our results offer not only renewed mechanistic insights into stacking and intercalation, but also open up prospects for engineering the functionality of TMDCs via stacking-selective self-intercalation.
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Affiliation(s)
- Hongguang Wang
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany.
| | - Jiawei Zhang
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Chen Shen
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt, Germany.
| | - Chao Yang
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Kathrin Küster
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Julia Deuschle
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Ulrich Starke
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Hongbin Zhang
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt, Germany
| | - Masahiko Isobe
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Dennis Huang
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany.
| | - Peter A van Aken
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Hidenori Takagi
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569, Stuttgart, Germany
- Department of Physics, University of Tokyo, 113-0033, Tokyo, Japan
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2
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Zhang Y, Qu W, Peng G, Zhang C, Liu Z, Liu J, Li S, Wu H, Meng L, Gao L. Seeing Structural Mechanisms of Optimized Piezoelectric and Thermoelectric Bulk Materials through Structural Defect Engineering. MATERIALS 2022; 15:ma15020487. [PMID: 35057205 PMCID: PMC8780573 DOI: 10.3390/ma15020487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/28/2021] [Accepted: 01/05/2022] [Indexed: 02/04/2023]
Abstract
Aberration-corrected scanning transmission electron microscopy (AC-STEM) has evolved into the most powerful characterization and manufacturing platform for all materials, especially functional materials with complex structural characteristics that respond dynamically to external fields. It has become possible to directly observe and tune all kinds of defects, including those at the crucial atomic scale. In-depth understanding and technically tailoring structural defects will be of great significance for revealing the structure-performance relation of existing high-property materials, as well as for foreseeing paths to the design of high-performance materials. Insights would be gained from piezoelectrics and thermoelectrics, two representative functional materials. A general strategy is highlighted for optimizing these functional materials’ properties, namely defect engineering at the atomic scale.
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Affiliation(s)
- Yang Zhang
- Instrumental Analysis Center of Xi’an Jiaotong University, Xi’an Jiaotong University, Xi’an 710049, China; (L.M.); (L.G.)
- Correspondence:
| | - Wanbo Qu
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China; (W.Q.); (G.P.); (C.Z.); (Z.L.); (J.L.); (S.L.); (H.W.)
| | - Guyang Peng
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China; (W.Q.); (G.P.); (C.Z.); (Z.L.); (J.L.); (S.L.); (H.W.)
| | - Chenglong Zhang
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China; (W.Q.); (G.P.); (C.Z.); (Z.L.); (J.L.); (S.L.); (H.W.)
| | - Ziyu Liu
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China; (W.Q.); (G.P.); (C.Z.); (Z.L.); (J.L.); (S.L.); (H.W.)
| | - Juncheng Liu
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China; (W.Q.); (G.P.); (C.Z.); (Z.L.); (J.L.); (S.L.); (H.W.)
| | - Shurong Li
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China; (W.Q.); (G.P.); (C.Z.); (Z.L.); (J.L.); (S.L.); (H.W.)
| | - Haijun Wu
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China; (W.Q.); (G.P.); (C.Z.); (Z.L.); (J.L.); (S.L.); (H.W.)
| | - Lingjie Meng
- Instrumental Analysis Center of Xi’an Jiaotong University, Xi’an Jiaotong University, Xi’an 710049, China; (L.M.); (L.G.)
| | - Lumei Gao
- Instrumental Analysis Center of Xi’an Jiaotong University, Xi’an Jiaotong University, Xi’an 710049, China; (L.M.); (L.G.)
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3
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Sarott MF, Gradauskaite E, Nordlander J, Strkalj N, Trassin M. In situmonitoring of epitaxial ferroelectric thin-film growth. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:293001. [PMID: 33873174 DOI: 10.1088/1361-648x/abf979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
In ferroelectric thin films, the polarization state and the domain configuration define the macroscopic ferroelectric properties such as the switching dynamics. Engineering of the ferroelectric domain configuration during synthesis is in permanent evolution and can be achieved by a range of approaches, extending from epitaxial strain tuning over electrostatic environment control to the influence of interface atomic termination. Exotic polar states are now designed in the technologically relevant ultrathin regime. The promise of energy-efficient devices based on ultrathin ferroelectric films depends on the ability to create, probe, and manipulate polar states in ever more complex epitaxial architectures. Because most ferroelectric oxides exhibit ferroelectricity during the epitaxial deposition process, the direct access to the polarization emergence and its evolution during the growth process, beyond the realm of existing structuralin situdiagnostic tools, is becoming of paramount importance. We review the recent progress in the field of monitoring polar states with an emphasis on the non-invasive probes allowing investigations of polarization during the thin film growth of ferroelectric oxides. A particular importance is given to optical second harmonic generationin situ. The ability to determine the net polarization and domain configuration of ultrathin films and multilayers during the growth of multilayers brings new insights towards a better understanding of the physics of ultrathin ferroelectrics and further control of ferroelectric-based heterostructures for devices.
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Affiliation(s)
- Martin F Sarott
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Elzbieta Gradauskaite
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Johanna Nordlander
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Nives Strkalj
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Morgan Trassin
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
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4
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Tian J, Zhang Y, Fan Z, Wu H, Zhao L, Rao J, Chen Z, Guo H, Lu X, Zhou G, Pennycook SJ, Gao X, Liu JM. Nanoscale Phase Mixture and Multifield-Induced Topotactic Phase Transformation in SrFeO x. ACS APPLIED MATERIALS & INTERFACES 2020; 12:21883-21893. [PMID: 32314574 DOI: 10.1021/acsami.0c03684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Nanoscale phase mixtures in transition-metal oxides (TMOs) often render these materials susceptible to external stimuli (electric field, mechanical stress, etc.), which can lead to rich functional properties and device applications. Here, direct observation and multifield manipulation of a nanoscale mixture of brownmillerite SrFeO2.5 (BM-SFO) and perovskite SrFeO3 (PV-SFO) phases in SrFeOx (SFO) epitaxial thin films are reported. The mixed-phase SFO film in its pristine state exhibits a nanoscaffold structure consisting of PV-SFO nanodomains embedded in the BM-SFO matrix. This nanoscaffold structure produces gridlike patterns in the current and electrochemical strain maps, owing to the strikingly different electrical and electrochemical properties of BM-SFO and PV-SFO. Moreover, electric field control of reversible topotactic phase transformation between BM-SFO and PV-SFO is demonstrated by electric-field-induced reversible changes in surface height, conductance, and electrochemical strain response. In addition, it is also shown that the BM-SFO → PV-SFO phase transformation can be enabled by applying mechanical stress. This study therefore not only identifies a strong nanometric structure-property correlation in the mixed-phase SFO but also offers a new paradigm for the multifield control of topotactic phase transformation.
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Affiliation(s)
- Junjiang Tian
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
| | - Yang Zhang
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- Instrumental Analysis Center of Xi'an Jiaotong University, Xi'an Jiaotong University, Xi'an 710049, China
| | - Zhen Fan
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
| | - Haijun Wu
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
| | - Lei Zhao
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
| | - Jingjing Rao
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
| | - Zuhuang Chen
- School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen 518055, China
| | - Haizhong Guo
- School of Physical Engineering, Zhengzhou University, Zhengzhou 450001, China
| | - Xubing Lu
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, China
| | - Stephen J Pennycook
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Xingsen Gao
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
| | - Jun-Ming Liu
- Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
- Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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5
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Wallum A, Nguyen HA, Gruebele M. Excited-State Imaging of Single Particles on the Subnanometer Scale. Annu Rev Phys Chem 2020; 71:415-433. [DOI: 10.1146/annurev-physchem-071119-040108] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
At the intersection of spectroscopy and microscopy lie techniques that are capable of providing subnanometer imaging of excited states of individual molecules or nanoparticles. Such approaches are particularly important for imaging macromolecules or nanoparticles large enough to have a high probability of containing a defect. These inevitable defects often control properties and function despite an otherwise ideal structure. We discuss real-space imaging techniques such as using scanning tunneling microscopy tips to enhance optical measurements and electron energy-loss spectroscopy in a scanning transmission electron microscope, which is based on focused electron beams to obtain high-resolution spatial information on excited states. The outlook for these methods is bright, as they will provide critical information for the characterization and improvement of energy-switching, electron-switching, and energy-harvesting materials.
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Affiliation(s)
- Alison Wallum
- Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Huy A. Nguyen
- Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Martin Gruebele
- Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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6
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Qin B, Zhang Y, Wang D, Zhao Q, Gu B, Wu H, Zhang H, Ye B, Pennycook SJ, Zhao LD. Ultrahigh Average ZT Realized in p-Type SnSe Crystalline Thermoelectrics through Producing Extrinsic Vacancies. J Am Chem Soc 2020; 142:5901-5909. [PMID: 32125832 DOI: 10.1021/jacs.0c01726] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Crystalline SnSe has been revealed as an efficient thermoelectric candidate with outstanding performance. Herein, record-high thermoelectric performance is achieved among SnSe crystals via simply introducing a small amount of SnSe2 as a kind of extrinsic defect dopant. This excellent performance mainly arises from the largely enhanced power factor by increasing the carrier concentration high as 6.55 × 1019 cm-3, which was surprisingly promoted by introducing extrinsic SnSe2 even though pristine SnSe2 is an n-type conductor. The optimized carrier concentration promotes a deeper Fermi level and activates more valence bands, leading to an extraordinary room-temperature power factor ∼54 μW cm-1 K-2 through enlarging the band effective mass and Seebeck coefficient. As a result, on the basis of simultaneously depressed thermal conductivity induced from both Sn vacancies and SnSe2 microdomains, maximum ZT values ∼0.9-2.2 and excellent average ZT > 1.7 among the working temperature range are achieved in Na doped SnSe crystals with 2% extrinsic SnSe2. Our investigation illustrates new approaches on improving thermoelectric performance through introducing defect dopants, which might be well-implemented in other thermoelectric systems.
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Affiliation(s)
- Bingchao Qin
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Yang Zhang
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Dongyang Wang
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Qian Zhao
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Bingchuan Gu
- State Key Laboratory of Particle Detection and Electronics & Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Haijun Wu
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Hongjun Zhang
- State Key Laboratory of Particle Detection and Electronics & Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Bangjiao Ye
- State Key Laboratory of Particle Detection and Electronics & Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Stephen J Pennycook
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Li-Dong Zhao
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
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7
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Braidy N, Béchu A, Souza Terra JC, Patience GS. Experimental methods in chemical engineering: Transmission electron microscopy—TEM. CAN J CHEM ENG 2020. [DOI: 10.1002/cjce.23692] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Nadi Braidy
- Department of Chemical and Biotechnological EngineeringUniversité de Sherbrooke Sherbrooke Québec Canada
- Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke Sherbrooke Québec Canada
| | - Aude Béchu
- Department of ChemistryMcGill University Montreal Québec Canada
| | | | - Gregory S. Patience
- Department of Chemical Engineering, Polytechnique Montréal Montréal Québec Canada
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8
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Xiao Y, Wang D, Zhang Y, Chen C, Zhang S, Wang K, Wang G, Pennycook SJ, Snyder GJ, Wu H, Zhao LD. Band Sharpening and Band Alignment Enable High Quality Factor to Enhance Thermoelectric Performance in n-Type PbS. J Am Chem Soc 2020; 142:4051-4060. [DOI: 10.1021/jacs.0c00306] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Yu Xiao
- School of Materials Science and Engineering, Beihang University, Beijing 100191, P. R. China
| | - Dongyang Wang
- School of Materials Science and Engineering, Beihang University, Beijing 100191, P. R. China
| | - Yang Zhang
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Congrun Chen
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Shuxuan Zhang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Kedong Wang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Guangtao Wang
- School of Physics, Henan Normal University, Xinxiang 453007, P. R. China
| | - Stephen J. Pennycook
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - G. Jeffrey Snyder
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Haijun Wu
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Li-Dong Zhao
- School of Materials Science and Engineering, Beihang University, Beijing 100191, P. R. China
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9
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Braidy N, Gosselin R. Unmixing noisy co-registered spectrum images of multicomponent nanostructures. Sci Rep 2019; 9:18797. [PMID: 31827162 PMCID: PMC6906416 DOI: 10.1038/s41598-019-55219-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 11/13/2019] [Indexed: 11/12/2022] Open
Abstract
Analytical electron microscopy plays a key role in the development of novel nanomaterials. Electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDX) datasets are typically processed to isolate the background-subtracted elemental signal. Multivariate tools have emerged as powerful methods to blindly map the components, which addresses some of the shortcomings of the traditional methods. Here, we demonstrate the superior performance of a new multivariate optimization method using a challenging EELS and EDX dataset. The dataset was recorded from a spectrum image P-type metal-oxide-semiconductor stack with 7 components exhibiting heavy spectral overlap and a low signal-to-noise ratio. Compared to peak integration, independent component analysis, Baysian Linear Unmixing and Non-negative matrix factorization, the method proposed was the only one to identify the EELS spectra of all 7 components with the corresponding abundance profiles. Using the abundance of each component, it was possible to retrieve the EDX spectra of all the components, which were otherwise impossible to isolate, regardless of the method used. We expect that this robust method will bring a significant improvement for the chemical analysis of nanomaterials, especially for weak signals, dose-sensitive specimen or signals suffering heavy spectral overlap.
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Affiliation(s)
- Nadi Braidy
- Department of Chemical Engineering and Biotechnological Engineering, Université de Sherbrooke. 2500 Boul, de l'Université, Sherbrooke, PQ, J1K 2R1, Canada. .,Institut Interdisciplinaire d'Innovation Technologique (3IT), Sherbrooke, PQ, J1K 0A5, Canada.
| | - Ryan Gosselin
- Department of Chemical Engineering and Biotechnological Engineering, Université de Sherbrooke. 2500 Boul, de l'Université, Sherbrooke, PQ, J1K 2R1, Canada.,Institut Interdisciplinaire d'Innovation Technologique (3IT), Sherbrooke, PQ, J1K 0A5, Canada
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10
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He W, Wang D, Wu H, Xiao Y, Zhang Y, He D, Feng Y, Hao YJ, Dong JF, Chetty R, Hao L, Chen D, Qin J, Yang Q, Li X, Song JM, Zhu Y, Xu W, Niu C, Li X, Wang G, Liu C, Ohta M, Pennycook SJ, He J, Li JF, Zhao LD. High thermoelectric performance in low-cost SnS0.91Se0.09 crystals. Science 2019; 365:1418-1424. [DOI: 10.1126/science.aax5123] [Citation(s) in RCA: 277] [Impact Index Per Article: 55.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 04/26/2019] [Accepted: 08/30/2019] [Indexed: 12/17/2022]
Abstract
Thermoelectric technology allows conversion between heat and electricity. Many good thermoelectric materials contain rare or toxic elements, so developing low-cost and high-performance thermoelectric materials is warranted. Here, we report the temperature-dependent interplay of three separate electronic bands in hole-doped tin sulfide (SnS) crystals. This behavior leads to synergistic optimization between effective mass (m*) and carrier mobility (μ) and can be boosted through introducing selenium (Se). This enhanced the power factor from ~30 to ~53 microwatts per centimeter per square kelvin (μW cm−1 K−2 at 300 K), while lowering the thermal conductivity after Se alloying. As a result, we obtained a maximum figure of merit ZT (ZTmax) of ~1.6 at 873 K and an average ZT (ZTave) of ~1.25 at 300 to 873 K in SnS0.91Se0.09 crystals. Our strategy for band manipulation offers a different route for optimizing thermoelectric performance. The high-performance SnS crystals represent an important step toward low-cost, Earth-abundant, and environmentally friendly thermoelectrics.
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11
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Tao H, Wu H, Liu Y, Zhang Y, Wu J, Li F, Lyu X, Zhao C, Xiao D, Zhu J, Pennycook SJ. Ultrahigh Performance in Lead-Free Piezoceramics Utilizing a Relaxor Slush Polar State with Multiphase Coexistence. J Am Chem Soc 2019; 141:13987-13994. [PMID: 31397576 DOI: 10.1021/jacs.9b07188] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Owing to growing environmental concerns, the development of lead-free piezoelectrics with comparable performance to the benchmark Pb(Zr,Ti)O3 (PZT) becomes of great urgency. However, a further enhancement of lead-free piezoelectrics based on existing strategies has reached a bottleneck. Here we achieve a slush polar state with multiphase coexistence in lead-free potassium-sodium niobate (KNN) piezoceramics, which shows a novel relaxor behavior, i.e., frequency dispersion at the transition between different ferroelectric phases. It is very different from the conventional relaxor behavior which occurs at the paraelectric-ferroelectric phase transition. We obtain an ultrahigh piezoelectric coefficient (d33) of 650 ± 20 pC/N, the largest value of nontextured KNN-based ceramics, outperforming that of the commercialized PZT-5H. Atomic-resolution polarization mapping by Z-contrast imaging from different orientations reveals the entire material to comprise polar nanoregions with multiphase coexistence, which is again very different from conventional ferroelectric relaxors which have polar domains within a nonpolar matrix. Theoretical simulations validate the significantly decreased energy barrier and polarization anisotropy, which is facilitated by the high-density domain boundaries with easy polarization rotation bridging the multiphase-coexisting nanodomains. This work demonstrates a new strategy for designing lead-free piezoelectrics with further enhanced performance, which should also be applicable to other functional materials requiring a slush (flexible) state with respect to external stimulus.
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Affiliation(s)
- Hong Tao
- Department of Materials Science , Sichuan University , Chengdu 610064 , China
| | - Haijun Wu
- Department of Materials Science and Engineering , National University of Singapore , Singapore 117575 , Singapore
| | - Yao Liu
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education , Xi'an Jiaotong University , Xi'an , China
| | - Yang Zhang
- Department of Materials Science and Engineering , National University of Singapore , Singapore 117575 , Singapore
| | - Jiagang Wu
- Department of Materials Science , Sichuan University , Chengdu 610064 , China
| | - Fei Li
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education , Xi'an Jiaotong University , Xi'an , China
| | - Xiang Lyu
- Department of Materials Science , Sichuan University , Chengdu 610064 , China
| | - Chunlin Zhao
- Department of Materials Science , Sichuan University , Chengdu 610064 , China
| | - Dingquan Xiao
- Department of Materials Science , Sichuan University , Chengdu 610064 , China
| | - Jianguo Zhu
- Department of Materials Science , Sichuan University , Chengdu 610064 , China
| | - Stephen J Pennycook
- Department of Materials Science and Engineering , National University of Singapore , Singapore 117575 , Singapore
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12
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Hong M, Wang Y, Feng T, Sun Q, Xu S, Matsumura S, Pantelides ST, Zou J, Chen ZG. Strong Phonon-Phonon Interactions Securing Extraordinary Thermoelectric Ge 1- xSb xTe with Zn-Alloying-Induced Band Alignment. J Am Chem Soc 2019; 141:1742-1748. [PMID: 30592419 DOI: 10.1021/jacs.8b12624] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The ability of substitution atoms to decrease thermal conductivity is usually ascribed to the enhanced phonon-impurity scattering by assuming the original phonon dispersion relations. In this study, we find that 10% SbGe alloying in GeTe modifies the phonon dispersions significantly, closes the acoustic-optical phonon band gap, increases the phonon-phonon scattering rates, and reduces the phonon group velocities. These changes, together with grain boundaries, nanoprecipitates, and planar vacancies, lead to a significant decrease in the lattice thermal conductivity. In addition, an extra 2-6% Zn alloying decreases the energy offset between valence band edges at L and Σ points in Ge1- xSb xTe that is found to be induced by the Ge 4s2 lone pairs. Since Zn is free of s2 lone pair electrons, substituting Ge with Zn atoms can consequently diminish the Ge 4s2 lone-pair characters and reduce the energy offset, resulting in two energetically merged valence band maxima. The refined band structures render a power factor up to 40 μW cm-1 K-2 in Ge0.86Sb0.1Zn0.04Te. Ultimately, a superhigh zT of 2.2 is achieved. This study clarifies the impacts of high-concentration substitutional atoms on phonon band structure, phonon-phonon scattering rates, and the convergence of electron valence band edges, which could provide guidelines for developing high-performance thermoelectric materials.
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Affiliation(s)
- Min Hong
- Centre for Future Materials , University of Southern Queensland , Springfield , Queensland 4300 , Australia.,Materials Engineering , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Yuan Wang
- Centre for Future Materials , University of Southern Queensland , Springfield , Queensland 4300 , Australia
| | - Tianli Feng
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science , Vanderbilt University , Nashville , Tennessee 37235 , United States.,Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Qiang Sun
- Materials Engineering , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Shengduo Xu
- Materials Engineering , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Syo Matsumura
- Department of Applied Quantum Physics and Nuclear Engineering , Kyushu University , Motooka 744 , Nishi-ku, Fukuoka 819-0395 , Japan
| | - Sokrates T Pantelides
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science , Vanderbilt University , Nashville , Tennessee 37235 , United States.,Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Jin Zou
- Materials Engineering , The University of Queensland , Brisbane , Queensland 4072 , Australia.,Centre for Microscopy and Microanalysis , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Zhi-Gang Chen
- Centre for Future Materials , University of Southern Queensland , Springfield , Queensland 4300 , Australia.,Materials Engineering , The University of Queensland , Brisbane , Queensland 4072 , Australia
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Qin B, Wang D, He W, Zhang Y, Wu H, Pennycook SJ, Zhao LD. Realizing High Thermoelectric Performance in p-Type SnSe through Crystal Structure Modification. J Am Chem Soc 2018; 141:1141-1149. [DOI: 10.1021/jacs.8b12450] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Bingchao Qin
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Dongyang Wang
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Wenke He
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Yang Zhang
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
| | - Haijun Wu
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
| | - Stephen J. Pennycook
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
| | - Li-Dong Zhao
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
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