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Zhang Y, Duan W, Yang Y, Zhao Z, Ren G, Zhang N, Zheng L, Chen J, Wang J, Sun T. Are 4f-Orbitals Engaged in Covalent Bonding Between Lanthanides and Triphenylphosphine Oxide? An Oxygen K-Edge X-ray Absorption Spectroscopy and Density Functional Theory Study. Inorg Chem 2024; 63:2597-2605. [PMID: 38266171 DOI: 10.1021/acs.inorgchem.3c03834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
The bonding covalency between trivalent lanthanides (Ln = La, Pr, Nd, Eu, Gd) and triphenylphosphine oxide (TPPO) is studied by X-ray absorption spectra (XAS) and density functional theory (DFT) calculations on the LnCl3(TPPO)3 complexes. The O, P, and Cl K-edge XAS for the single crystals of LnCl3(TPPO)3 were collected, and the spectra were interpreted based on DFT calculations. The O and P K-edge XAS spectra showed no significant change across the Ln series in the LnCl3(TPPO)3 complexes, unlike the Cl K-edge XAS spectra. The experimental O K-edge XAS spectra suggest no mixing between the Ln 4f- and the O 2p-orbitals in the LnCl3(TPPO)3 complexes. DFT calculations indicate that the amount of the O 2p character per Ln-O bond is less than 0.1% in the Ln 4f-based orbitals in all of the LnCl3(TPPO)3 complexes. The experimental spectra and theoretical calculations demonstrate that Ln 4f-orbitals are not engaged in the covalent bonding of lanthanides with TPPO, which contrasts the involvement of U 5f-orbitals in covalent bonding in the UO2Cl2(TPPO)2 complex. Results in this work reinforce our previous speculation that bonding covalency is potentially responsible for the extractability of monodentate organophosphorus ligands toward metal ions.
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Affiliation(s)
- Yusheng Zhang
- Xi'an Modern Chemistry Research Institute, Xi'an 710065, China
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Wuhua Duan
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Yuning Yang
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Zhijin Zhao
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Guoxi Ren
- Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Nian Zhang
- Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Lei Zheng
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Chen
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Jianchen Wang
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Taoxiang Sun
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
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2
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Yan X, Wrobel F, Tung IC, Zhou H, Hong H, Rodolakis F, Bhattacharya A, McChesney JL, Fong DD. Origin of the 2D Electron Gas at the SrTiO 3 Surface. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2200866. [PMID: 35429184 DOI: 10.1002/adma.202200866] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/04/2022] [Indexed: 06/14/2023]
Abstract
Bulk SrTiO3 is a well-known band insulator and the most common substrate used in the field of complex oxide heterostructures. Its surface and interface with other oxides, however, have demonstrated a variety of remarkable behaviors distinct from those expected. In this work, using a suite of in situ techniques to monitor both the atomic and electronic structures of the SrTiO3 (001) surface prior to and during growth, the disappearance and re-appearance of a 2D electron gas (2DEG) is observed after the completion of each SrO and TiO2 monolayer, respectively. The 2DEG is identified with the TiO2 double layer present at the initial SrTiO3 surface, which gives rise to a surface potential and mobile electrons due to vacancies within the TiO2-x adlayer. Much like the electronic reconstruction discovered in other systems, two atomic planes are required, here supplied by the double layer. The combined in situ scattering/spectroscopy findings resolve a number of longstanding issues associated with complex oxide interfaces, facilitating the employment of atomic-scale defect engineering in oxide electronics.
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Affiliation(s)
- Xi Yan
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Friederike Wrobel
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - I-Cheng Tung
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Hua Zhou
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Hawoong Hong
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Fanny Rodolakis
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Anand Bhattacharya
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Jessica L McChesney
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Dillon D Fong
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
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3
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Shao Z, Zhu Q, Sun Y, Zhang Y, Jiang Y, Deng S, Zhang W, Huang K, Feng S. Phase-Reconfiguration-Induced NiS/NiFe 2 O 4 Composite for Performance-Enhanced Zinc-Air Batteries. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2110172. [PMID: 35170104 DOI: 10.1002/adma.202110172] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Constructing composite structures is an essential approach for obtaining multiple functionalities in a single entity. Available synthesis methods of the composites need to be urgently exploited; especially in situ construction. Here, a NiS/NiFe2 O4 composite through a local metal-S coordination at the interface is reported, which is derived from phase reconstruction in the highly defective matrix. X-ray absorption fine structure confirms that long-range order is broken via the local metal-S coordination and, by using electron energy loss spectroscopy, the introduction of NiS/NiFe2 O4 interfaces during the irradiation of plasma energy is identified. Density functional theory (DFT) calculations reveal that in situ phase reconfiguration is crucial for synergistically reducing energetic barriers and accelerating reaction kinetics toward catalyzing the oxygen evolution reaction (OER). As a result; it leads to an overpotential of 230 mV @10 mA cm-2 for the OER and a half-wave potential of 0.81 V for the oxygen reduction reaction (ORR); as well as an excellent zinc-air battery (ZAB) performance with a power density of 148.5 mW cm-2 . This work provides a new compositing strategy in terms of fast phase reconstruction of bifunctional catalysts.
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Affiliation(s)
- Zhiyu Shao
- State Key Laboratory of Inorganic Synthesis and Preparative, Chemistry Jilin Provincial International Cooperation Key Laboratory of Advanced Inorganic Solid Functional Materials, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun, 130012, China
| | - Qian Zhu
- State Key Laboratory of Inorganic Synthesis and Preparative, Chemistry Jilin Provincial International Cooperation Key Laboratory of Advanced Inorganic Solid Functional Materials, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun, 130012, China
| | - Yu Sun
- School of Advanced Materials and Nanotechnology, Xidian University, Xi'an, 710126, China
| | - Yuan Zhang
- State Key Laboratory of Inorganic Synthesis and Preparative, Chemistry Jilin Provincial International Cooperation Key Laboratory of Advanced Inorganic Solid Functional Materials, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun, 130012, China
| | - Yilan Jiang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China
| | - Shiqing Deng
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing, 100083, China
- Key Laboratory of Advanced Materials of Ministry of Education, Tsinghua University, Beijing, 100084, China
| | - Wei Zhang
- Electron Microscopy Center, Jilin University, Changchun, 130012, China
| | - Keke Huang
- State Key Laboratory of Inorganic Synthesis and Preparative, Chemistry Jilin Provincial International Cooperation Key Laboratory of Advanced Inorganic Solid Functional Materials, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun, 130012, China
| | - Shouhua Feng
- State Key Laboratory of Inorganic Synthesis and Preparative, Chemistry Jilin Provincial International Cooperation Key Laboratory of Advanced Inorganic Solid Functional Materials, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun, 130012, China
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4
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Feng C, Xiong G, Jiang F, Gao Q, Chen C, Pan Y, Fei Z, Li Y, Lu Y, Liu C, Liu Y. Assembly of sphere-structured MnO2 for total oxidation of propane: Structure-activity relationship and reaction mechanism determination. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2021.120269] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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5
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Wu M, Zhang X, Li X, Qu K, Sun Y, Han B, Zhu R, Gao X, Zhang J, Liu K, Bai X, Li XZ, Gao P. Engineering of atomic-scale flexoelectricity at grain boundaries. Nat Commun 2022; 13:216. [PMID: 35017521 PMCID: PMC8752668 DOI: 10.1038/s41467-021-27906-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 12/17/2021] [Indexed: 12/05/2022] Open
Abstract
Flexoelectricity is a type of ubiquitous and prominent electromechanical coupling, pertaining to the electrical polarization response to mechanical strain gradients that is not restricted by the symmetry of materials. However, large elastic deformation is usually difficult to achieve in most solids, and the strain gradient at minuscule is challenging to control. Here, we exploit the exotic structural inhomogeneity of grain boundary to achieve a huge strain gradient (~1.2 nm-1) within 3-4-unit cells, and thus obtain atomic-scale flexoelectric polarization of up to ~38 μC cm-2 at a 24° LaAlO3 grain boundary. Accompanied by the generation of the nanoscale flexoelectricity, the electronic structures of grain boundaries also become different. Hence, the flexoelectric effect at grain boundaries is essential to understand the electrical activities of oxide ceramics. We further demonstrate that for different materials, altering the misorientation angles of grain boundaries enables tunable strain gradients at the atomic scale. The engineering of grain boundaries thus provides a general and feasible pathway to achieve tunable flexoelectricity.
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Affiliation(s)
- Mei Wu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Xiaowei Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Xiaomei Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Ke Qu
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Yuanwei Sun
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Bo Han
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Ruixue Zhu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Xiaoyue Gao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Jingmin Zhang
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Kaihui Liu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China
- Collaborative Innovation Centre of Quantum Matter, Beijing, 100871, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, 100871, China
| | - Xuedong Bai
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xin-Zheng Li
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China.
- Collaborative Innovation Centre of Quantum Matter, Beijing, 100871, China.
- Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871, China.
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, 226010, Jiangsu, China.
| | - Peng Gao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China.
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China.
- Collaborative Innovation Centre of Quantum Matter, Beijing, 100871, China.
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, 100871, China.
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6
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Song K, Min T, Seo J, Ryu S, Lee H, Wang Z, Choi S, Lee J, Eom C, Oh SH. Electronic and Structural Transitions of LaAlO 3 /SrTiO 3 Heterostructure Driven by Polar Field-Assisted Oxygen Vacancy Formation at the Surface. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2002073. [PMID: 34029001 PMCID: PMC8292910 DOI: 10.1002/advs.202002073] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 02/22/2021] [Indexed: 05/16/2023]
Abstract
The origin of 2D electron gas (2DEG) at LaAlO3 /SrTiO3 (LAO/STO) interfaces has remained highly controversial since its discovery. Various models are proposed, which include electronic reconstruction via surface-to-interface charge transfer and defect-mediated doping involving cation intermixing or oxygen vacancy (VO ) formation. It is shown that the polar field-assisted VO formation at the LAO/STO surface plays critical roles in the 2DEG formation and concurrent structural transition. Comprehensive scanning transmission electron microscopy analyses, in conjunction with density functional theory calculations, demonstrate that VO forming at the LAO/STO surface above the critical thickness (tc ) cancels the polar field by doping the interface with 2DEG. The antiferrodistortive (AFD) octahedral rotations in LAO, which are suppressed below the tc , evolve with the formation of VO above the tc . The present study reveals that local symmetry breaking and shallow donor behavior of VO induce the AFD rotations and relieve the electrical field by electron doping the oxide heterointerface.
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Affiliation(s)
- Kyung Song
- Materials Testing and Reliability DivisionKorea Institute of Materials Science (KIMS)Changwon51508Republic of Korea
- Department of Materials Science and EngineeringPohang University of Science and Technology (POSTECH)Pohang37673Republic of Korea
| | - Taewon Min
- Department of PhysicsPusan National UniversityBusan46241Republic of Korea
| | - Jinsol Seo
- Department of Energy ScienceSungkyunkwan UniversitySuwon16419Republic of Korea
| | - Sangwoo Ryu
- Department of Materials Science and EngineeringUniversity of Wisconsin‐MadisonMadisonWI53706USA
| | - Hyungwoo Lee
- Department of Materials Science and EngineeringUniversity of Wisconsin‐MadisonMadisonWI53706USA
| | - Zhipeng Wang
- Department of Energy ScienceSungkyunkwan UniversitySuwon16419Republic of Korea
| | - Si‐Young Choi
- Materials Testing and Reliability DivisionKorea Institute of Materials Science (KIMS)Changwon51508Republic of Korea
- Department of Materials Science and EngineeringPohang University of Science and Technology (POSTECH)Pohang37673Republic of Korea
| | - Jaekwang Lee
- Department of PhysicsPusan National UniversityBusan46241Republic of Korea
| | - Chang‐Beom Eom
- Department of Materials Science and EngineeringUniversity of Wisconsin‐MadisonMadisonWI53706USA
| | - Sang Ho Oh
- Department of Materials Science and EngineeringPohang University of Science and Technology (POSTECH)Pohang37673Republic of Korea
- Department of Energy ScienceSungkyunkwan UniversitySuwon16419Republic of Korea
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7
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Min T, Choi W, Seo J, Han G, Song K, Ryu S, Lee H, Lee J, Eom K, Eom CB, Jeong HY, Kim YM, Lee J, Oh SH. Cooperative evolution of polar distortion and nonpolar rotation of oxygen octahedra in oxide heterostructures. SCIENCE ADVANCES 2021; 7:7/17/eabe9053. [PMID: 33883134 PMCID: PMC8059930 DOI: 10.1126/sciadv.abe9053] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 03/05/2021] [Indexed: 05/23/2023]
Abstract
Polarity discontinuity across LaAlO3/SrTiO3 (LAO/STO) heterostructures induces electronic reconstruction involving the formation of two-dimensional electron gas (2DEG) and structural distortions characterized by antiferrodistortive (AFD) rotation and ferroelectric (FE) distortion. We show that AFD and FE modes are cooperatively coupled in LAO/STO (111) heterostructures; they coexist below the critical thickness (t c) and disappear simultaneously above t c with the formation of 2DEG. Electron energy-loss spectroscopy and density functional theory (DFT) calculations provide direct evidence of oxygen vacancy (V O) formation at the LAO (111) surface, which acts as the source of 2DEG. Tracing the AFD rotation and FE distortion of LAO reveals that their evolution is strongly correlated with V O distribution. The present study demonstrates that AFD and FE modes in oxide heterostructures emerge as a consequence of interplay between misfit strain and polar field, and further that their combination can be tuned to competitive or cooperative coupling by changing the interface orientation.
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Affiliation(s)
- Taewon Min
- Department of Physics, Pusan National University, Busan 46241, Republic of Korea
| | - Wooseon Choi
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jinsol Seo
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Gyeongtak Han
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Kyung Song
- Materials Testing and Reliability Division, Korea Institute of Materials Science (KIMS), Changwon 51508, Republic of Korea
| | - Sangwoo Ryu
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Hyungwoo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jungwoo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Kitae Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Hu Young Jeong
- UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Young-Min Kim
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.
| | - Jaekwang Lee
- Department of Physics, Pusan National University, Busan 46241, Republic of Korea.
| | - Sang Ho Oh
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.
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8
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Wu ZL, Xie H, Li Y, Zhang F, Wang Z, Zheng W, Yang M, Cao Y, Lu Z. Insights into the chemical and structural evolution of Li-rich layered oxide cathode materials. Inorg Chem Front 2021. [DOI: 10.1039/d0qi01021a] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lithium-rich layered oxide cathodes have an advantage of high energy density.
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Affiliation(s)
- Zhi-Liang Wu
- School of Chemistry and Materials Engineering
- Huizhou University
- Huizhou 516007
- China
- Department of Materials Science and Engineering
| | - Hanjie Xie
- Department of Materials Science and Engineering
- Guangdong Provincial Key Laboratory of Energy Materials for Electric Power
- Southern University of Science and Technology
- Shenzhen 518055
- China
| | - Yingzhi Li
- Department of Materials Science and Engineering
- Guangdong Provincial Key Laboratory of Energy Materials for Electric Power
- Southern University of Science and Technology
- Shenzhen 518055
- China
| | - Fangchang Zhang
- Department of Materials Science and Engineering
- Guangdong Provincial Key Laboratory of Energy Materials for Electric Power
- Southern University of Science and Technology
- Shenzhen 518055
- China
| | - Zhenyu Wang
- Department of Materials Science and Engineering
- Guangdong Provincial Key Laboratory of Energy Materials for Electric Power
- Southern University of Science and Technology
- Shenzhen 518055
- China
| | - Wei Zheng
- Department of Materials Science and Engineering
- Guangdong Provincial Key Laboratory of Energy Materials for Electric Power
- Southern University of Science and Technology
- Shenzhen 518055
- China
| | - Mingyang Yang
- Department of Materials Science and Engineering
- Guangdong Provincial Key Laboratory of Energy Materials for Electric Power
- Southern University of Science and Technology
- Shenzhen 518055
- China
| | - Yulin Cao
- Physics Laboratory
- Industrial Training Center
- Shenzhen Polytechnic
- Shenzhen 518055
- China
| | - Zhouguang Lu
- Department of Materials Science and Engineering
- Guangdong Provincial Key Laboratory of Energy Materials for Electric Power
- Southern University of Science and Technology
- Shenzhen 518055
- China
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9
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Abstract
We review oxygen K-edge X-ray absorption spectra of both molecules and solids. We start with an overview of the main experimental aspects of oxygen K-edge X-ray absorption measurements including X-ray sources, monochromators, and detection schemes. Many recent oxygen K-edge studies combine X-ray absorption with time and spatially resolved measurements and/or operando conditions. The main theoretical and conceptual approximations for the simulation of oxygen K-edges are discussed in the Theory section. We subsequently discuss oxygen atoms and ions, binary molecules, water, and larger molecules containing oxygen, including biomolecular systems. The largest part of the review deals with the experimental results for solid oxides, starting from s- and p-electron oxides. Examples of theoretical simulations for these oxides are introduced in order to show how accurate a DFT description can be in the case of s and p electron overlap. We discuss the general analysis of the 3d transition metal oxides including discussions of the crystal field effect and the effects and trends in oxidation state and covalency. In addition to the general concepts, we give a systematic overview of the oxygen K-edges element by element, for the s-, p-, d-, and f-electron systems.
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Affiliation(s)
- Federica Frati
- Inorganic
chemistry and catalysis, Debye Institute for Nanomaterials Science, Utrecht University, 3584CG Utrecht, The Netherlands
| | | | - Frank M. F. de Groot
- Inorganic
chemistry and catalysis, Debye Institute for Nanomaterials Science, Utrecht University, 3584CG Utrecht, The Netherlands
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10
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Chi X, Wang H, Guo R, Whitcher TJ, Yu X, Yang P, Yan X, Breese MBH, Loh KP, Chen J, Rusydi A. Unusual Hole and Electron Midgap States and Orbital Reconstructions Induced Huge Ferroelectric Tunneling Electroresistance in BaTiO 3/SrTiO 3. NANO LETTERS 2020; 20:1101-1109. [PMID: 31944125 DOI: 10.1021/acs.nanolett.9b04390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Oxide heterostructures have attracted a lot of interest because of their rich exotic phenomena and potential applications. Recently, a greatly enhanced tunneling electroresistance (TER) of ferroelectric tunnel junctions (FTJs) has been realized in such heterostructures. However, our understanding on the electronic structure of resistance response with polarization reversal and the origin of huge TER is still lacking. Here, we report on electronic structures, particularly at the interface and surface, and the control of the spontaneous polarization of BaTiO3 films by changing the termination of a SrTiO3 substrate. Interestingly, unusual electron and hole midgap states are concurrently formed and accompanied by orbital reconstructions, which determine the ferroelectric polarization orientation in the BaTiO3/SrTiO3. Such unusual midgap states, which yield a strong electronic screening effect, reduce the ferroelectric barrier width and height, and pin the ferroelectric polarization, lead to a dramatic enhancement of the TER effect. The midgap states are also observed in BaTiO3 films on electron-doped Nb/SrTiO3 revealing its universality. Our result provides new insight into the origin of the huge TER effect and opens a new route for designing ferroelectric tunnel junction-based devices with huge TER through interface engineering.
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Affiliation(s)
- Xiao Chi
- Singapore Synchrotron Light Source , National University of Singapore , 5 Research Link, 117603 , Singapore
- Department of Chemistry , National University of Singapore , 3 Science Drive 3, 117543 , Singapore
- Center for Advanced 2D Materials and Graphene Research Centre , 2 Science Drive 2, 117526 , Singapore
| | - Han Wang
- Department of Materials Science and Engineering , National University of Singapore , 117575 , Singapore
| | - Rui Guo
- Department of Materials Science and Engineering , National University of Singapore , 117575 , Singapore
| | - Thomas J Whitcher
- Singapore Synchrotron Light Source , National University of Singapore , 5 Research Link, 117603 , Singapore
- Center for Advanced 2D Materials and Graphene Research Centre , 2 Science Drive 2, 117526 , Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source , National University of Singapore , 5 Research Link, 117603 , Singapore
| | - Ping Yang
- Singapore Synchrotron Light Source , National University of Singapore , 5 Research Link, 117603 , Singapore
| | - Xiaobing Yan
- Department of Materials Science and Engineering , National University of Singapore , 117575 , Singapore
| | - Mark B H Breese
- Singapore Synchrotron Light Source , National University of Singapore , 5 Research Link, 117603 , Singapore
- Department of Physics , National University of Singapore , 2 Science Drive 3, 117542 , Singapore
| | - Kian Ping Loh
- Department of Chemistry , National University of Singapore , 3 Science Drive 3, 117543 , Singapore
- Center for Advanced 2D Materials and Graphene Research Centre , 2 Science Drive 2, 117526 , Singapore
- Solar Energy Research Institute of Singapore (SERIS) , 7 Engineering Drive 1, 117574 , Singapore
| | - Jingsheng Chen
- Department of Chemistry , National University of Singapore , 3 Science Drive 3, 117543 , Singapore
| | - Andrivo Rusydi
- Singapore Synchrotron Light Source , National University of Singapore , 5 Research Link, 117603 , Singapore
- Department of Physics , National University of Singapore , 2 Science Drive 3, 117542 , Singapore
- Center for Advanced 2D Materials and Graphene Research Centre , 2 Science Drive 2, 117526 , Singapore
- Solar Energy Research Institute of Singapore (SERIS) , 7 Engineering Drive 1, 117574 , Singapore
- NUSSNI-NanoCore , National University of Singapore , 117576 , Singapore
- Graduate School for Integrative Sciences and Engineering (NGS) , National University of Singapore , 28 Medical Drive, 117456 , Singapore
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11
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Liao X, Zhang Y, Wang J, Kang J, Zhang J, Wang J, Zheng J, Wang H. Resistance Switching Behavior in Rectangle-Nano-Pattern SrTiO 3 Induced by Simple Annealing. MATERIALS (BASEL, SWITZERLAND) 2019; 12:ma12223698. [PMID: 31717524 PMCID: PMC6888333 DOI: 10.3390/ma12223698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/31/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
The tunability of semi-conductivity in SrTiO3 single crystal substrates has been realized by a simple encapsulated annealing method under argon atmosphere. This high temperature annealing-induced property changes are characterized by the transmission spectra, scanning electron microscopy (SEM) and synchrotron-based X-ray absorption (XAS). We find the optical property is strongly influenced by the annealing time (with significant decrease of transmittance). A sub gap absorption at ~427 nm is detected which is attributed to the introduction of oxygen vacancy. Interestingly, in the SEM images, annealing-induced regularly rectangle nano-patterns are directly observed which is contributed to the conducting filaments. The XAS of O K-edge spectra shows the changes of electronic structure by annealing. Very importantly, resistance switching response is displayed in the annealed SrTiO3 single crystal. This suggests a possible simplified route to tune the conductivity of SrTiO3 and further develop novel resistance switching materials.
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Affiliation(s)
- Xiaxia Liao
- School of Materials Science and Engineering, Nanchang University, Nanchang 330031, China;
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
| | - Yufeng Zhang
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
| | - Jiaou Wang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049, China;
| | - Junyong Kang
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
| | - Jinbin Zhang
- College of Materials, Xiamen University, Xiamen 361005, China;
| | - Jizheng Wang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
| | - Jincheng Zheng
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
- Institute of Artificial Intelligence, Xiamen University Malaysia, Sepang 43900, Malaysia
| | - Huiqiong Wang
- Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China; (Y.Z.); (J.K.)
- Institute of Artificial Intelligence, Xiamen University Malaysia, Sepang 43900, Malaysia
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Chi X, Huang Z, Asmara TC, Han K, Yin X, Yu X, Diao C, Yang M, Schmidt D, Yang P, Trevisanutto PE, Whitcher TJ, Venkatesan T, Breese MBH, Rusydi A. Large Enhancement of 2D Electron Gases Mobility Induced by Interfacial Localized Electron Screening Effect. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1707428. [PMID: 29667241 DOI: 10.1002/adma.201707428] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/13/2018] [Indexed: 06/08/2023]
Abstract
The interactions between delocalized and localized charges play important roles in correlated electron systems. Here, using a combination of transport measurements, spectroscopic ellipsometry (SE), and X-ray absorption spectroscopy (XAS) supported by theoretical calculations, we reveal the important role of interfacial localized charges and their screening effects in determining the mobility of (La0.3 Sr0.7 )(Al0.65 Ta0.35 )O3 /SrTiO3 (LSAT/SrTiO3 ) interfaces. When the LSAT layer thickness reaches the critical value of 5 uc, the insulating interface abruptly becomes conducting, accompanied by the appearance of a new midgap state. This midgap state emerges at ≈1 eV below the Ti t2g band and shows a strong character of Ti 3dxy - O 2p hybridization. Increasing the LSAT layer from 5 to 18 uc, the number of localized charges increases, resulting in an enhanced screening effect and higher mobile electron mobility. This observation contradicts the traditional semiconductor interface where the localized charges always suppress the carrier mobility. These results demonstrate a new strategy to probe localized charges and mobile electrons in correlated electronic systems and highlight the important role of screening effects from localized charges in improving the mobile electron mobility at complex oxide interfaces.
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Affiliation(s)
- Xiao Chi
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Zhen Huang
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - Teguh C Asmara
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - Kun Han
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - Xinmao Yin
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Caozheng Diao
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Ming Yang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore
- Institute of Materials Research and Engineering, A*-STAR, 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Daniel Schmidt
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Ping Yang
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Paolo E Trevisanutto
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - T J Whitcher
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - T Venkatesan
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore, 117456, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Mark B H Breese
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Andrivo Rusydi
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore, 117456, Singapore
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Electrons and Polarons at Oxide Interfaces Explored by Soft-X-Ray ARPES. SPECTROSCOPY OF COMPLEX OXIDE INTERFACES 2018. [DOI: 10.1007/978-3-319-74989-1_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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15
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Palina N, Wang L, Dash S, Yu X, Breese MBH, Wang J, Rusydi A. Investigation of the metal-insulator transition in NdNiO 3 films by site-selective X-ray absorption spectroscopy. NANOSCALE 2017; 9:6094-6102. [PMID: 28447095 DOI: 10.1039/c7nr00742f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this work, multifunctional oxide NdNiO3 (NNO) thin films grown on a SrTiO3 (STO) substrate using pulsed-laser deposition are studied. Temperature dependent resistivity measurements revealed that NNO/STO samples exhibit a sharp thickness dependent metal-insulator transition (MIT) over a range of 150-200 K. It is known that the electronic properties of correlated oxides are extremely complex and sensitive to changes in orbital occupancy. To evaluate the changes in the electronic and/or crystallographic structure responsible for the MIT, a site-selective (O, Ni and Nd) X-ray absorption near edge structure (XANES) analysis is performed above and below the transition temperature. Analysis of XANES spectra suggests that: (i) in NNO films nominally trivalent Ni ions exhibit multiple valency (bond disproportionation), (ii) intermetallic hybridization plays an important role, (iii) the presence of strong O 2p-O 2p hole correlation at low temperature results in the opening of the p-p gap and (iv) the valency of Nd ions matches well with that of Nd3+. For NNO films exhibiting a sharp MIT, Ni 3d electron localization and concurrent existence of Ni 3d8 and Ni 3d8L[combining low line]2 states are responsible for the observed transition. At temperatures below the MIT the O 2p-O 2p hole correlation is strong enough to split the O 2p band stabilizing insulating phase. Temperature and thickness dependent differences observed in the site-selective XANES data are discussed in terms of possible mechanisms for the MIT (negative charge-transfer type).
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Affiliation(s)
- Natalia Palina
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore. and NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - Le Wang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Sibashisa Dash
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore. and School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore and Department of Applied Physics, Waseda University, Shinjuku, Tokyo 169-8555, Japan
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore.
| | - Mark B H Breese
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore. and Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Junling Wang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Andrivo Rusydi
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore. and NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore and Department of Physics, National University of Singapore, Singapore 117542, Singapore
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Lee M, Arras R, Warot-Fonrose B, Hungria T, Lippmaa M, Daimon H, Casanove MJ. Strain induced atomic structure at the Ir-doped LaAlO3/SrTiO3 interface. Phys Chem Chem Phys 2017; 19:28676-28683. [DOI: 10.1039/c7cp05918c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Different levels of Ir doping at the LaAlO3/SrTiO3 interface affect the strain state in LaAlO3, as investigated using atomically resolved microscopy (HAADF-STEM), electron energy loss spectroscopy (EELS) and first-principles calculations (DFT).
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Affiliation(s)
- M. Lee
- Centre d’Elaboration des Matériaux et d’Etudes Structurales (CEMES)
- CNRS UPR 8011 and Université de Toulouse
- F-31055 Toulouse
- France
- Nara Institute of Science and Technology (NAIST)
| | - R. Arras
- Centre d’Elaboration des Matériaux et d’Etudes Structurales (CEMES)
- CNRS UPR 8011 and Université de Toulouse
- F-31055 Toulouse
- France
| | - B. Warot-Fonrose
- Centre d’Elaboration des Matériaux et d’Etudes Structurales (CEMES)
- CNRS UPR 8011 and Université de Toulouse
- F-31055 Toulouse
- France
| | - T. Hungria
- Centre de MicroCaractérisation Raimond Castaing
- Université de Toulouse
- F-31400 Toulouse
- France
| | - M. Lippmaa
- Institute for Solid State Physics
- University of Tokyo
- 277-8581 Chiba
- Japan
| | - H. Daimon
- Nara Institute of Science and Technology (NAIST)
- Ikoma 630-0192
- Japan
| | - M. J. Casanove
- Centre d’Elaboration des Matériaux et d’Etudes Structurales (CEMES)
- CNRS UPR 8011 and Université de Toulouse
- F-31055 Toulouse
- France
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