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Namba M, Takatsu H, Mikita R, Sijia Y, Murayama K, Li HB, Terada R, Tassel C, Ubukata H, Ochi M, Saez-Puche R, Latasa EP, Ishimatsu N, Shiga D, Kumigashira H, Kinjo K, Kitagawa S, Ishida K, Terashima T, Fujita K, Mashiko T, Yanagisawa K, Kimoto K, Kageyama H. Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO 2H Films. J Am Chem Soc 2023; 145:21807-21816. [PMID: 37770040 DOI: 10.1021/jacs.3c04521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Perovskite oxides ABO3 continue to be a major focus in materials science. Of particular interest is the interplay between A and B cations as exemplified by intersite charge transfer (ICT), which causes novel phenomena including negative thermal expansion and metal-insulator transition. However, the ICT properties were achieved and optimized by cationic substitution or ordering. Here we demonstrate an anionic approach to induce ICT using an oxyhydride perovskite, EuVO2H, which has alternating layers of EuH and VO2. A bulk EuVO2H behaves as a ferromagnetic insulator with a relatively high transition temperature (TC) of 10 K. However, the application of external pressure to the EuIIVIIIO2H bulk or compressive strain from the substrate in the thin films induces ICT from the EuIIH layer to the VIIIO2 layer due to the extended empty V dxy orbital. The ICT phenomenon causes the VO2 layer to become conductive, leading to an increase in TC that is dependent on the number of carriers in the dxy orbitals (up to a factor of 4 for 10 nm thin films). In addition, a large perpendicular magnetic anisotropy appears with the ICT for the films of <100 nm, which is unprecedented in materials with orbital-free Eu2+, opening new perspectives for applications. The present results provide opportunities for the acquisition of novel functions by alternating transition metal/rare earth layers with heteroanions.
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Affiliation(s)
- Morito Namba
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Hiroshi Takatsu
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Riho Mikita
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Yao Sijia
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Kantaro Murayama
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Hao-Bo Li
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Ryo Terada
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Cédric Tassel
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Hiroki Ubukata
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Masayuki Ochi
- Department of Physics, Osaka University, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
- Forefront Research Center, Osaka University, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Regino Saez-Puche
- Departamento Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria, 28040, Madrid, Spain
| | - Elias Palacios Latasa
- INMA, CSIC-Universidad de Zaragoza, 50009, Zaragoza, Spain
- Departamento de Ciencia y Tecnología de Materiales y Fluidos, Universidad de Zaragoza, 50018, Zaragoza, Spain
| | - Naoki Ishimatsu
- Department of Physical Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
| | - Daisuke Shiga
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
| | | | - Katsuki Kinjo
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Shunsaku Kitagawa
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Kenji Ishida
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Takahito Terashima
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Koji Fujita
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Takeaki Mashiko
- National Institute for Materials Science, Ibaraki 305-0044, Japan
| | | | - Koji Kimoto
- National Institute for Materials Science, Ibaraki 305-0044, Japan
| | - Hiroshi Kageyama
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
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2
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Wadhwa P, Bosin A, Filippetti A. Ultra-thin magnetic film with giant phonon-drag for heat to spin current conversion. MATERIALS HORIZONS 2023; 10:3559-3568. [PMID: 37303227 DOI: 10.1039/d3mh00584d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A tightly confined 2D electron gas with good carrier mobility and large spin-polarization is an essential ingredient for the implementation of spin-caloritronic conversion device technology. Here we give evidence that the SrTiO3/EuTiO3/LaAlO3 heterostructure is a prototype material for this purpose. The presence of Eu induces strong spin-polarization in the 2D electron gas spontaneously formed at the interface and ferromagnetic order at low temperature. Furthermore, tight 2D confinement and spin-polarization can be highly enhanced upon charge depletion, in turn generating huge thermopower associated with the phonon-drag mechanism. Most importantly, the remarkable difference in the population of the two spin channels results in the giant spin-polarized Seebeck effect and in turn, giant spin voltages of mV K-1 order at the two ends of an applied thermal gradient. Our results represent a strong assessment to the capabilities of this interface for low-temperature spin-caloritronic applications.
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Affiliation(s)
- Payal Wadhwa
- Dipartimento di Fisica, Università di Cagliari, S.P. Monserrato Sestu Km.0,700, Monserrato (Ca) 09042-I, Italy
| | - Andrea Bosin
- Dipartimento di Fisica, Università di Cagliari, S.P. Monserrato Sestu Km.0,700, Monserrato (Ca) 09042-I, Italy
| | - Alessio Filippetti
- Dipartimento di Fisica, Università di Cagliari, S.P. Monserrato Sestu Km.0,700, Monserrato (Ca) 09042-I, Italy
- Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali, CNR-IOM, S.P. Monserrato Sestu Km.0,700, Monserrato (Ca) 09042-I, Italy.
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3
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Abstract
Hydrogen is considered a promising clean energy vector with the features of high energy capacity and zero-carbon emission. Water splitting is an environment-friendly and effective route for producing high-purity hydrogen, which contains two important half-cell reactions, namely, the anodic oxygen evolution reaction (OER) and the cathodic hydrogen evolution reaction (HER). At the heart of water splitting is high-performance electrocatalysts that efficiently improve the rate and selectivity of key chemical reactions. Recently, perovskite oxides have emerged as promising candidates for efficient water splitting electrocatalysts owing to their low cost, high electrochemical stability, and compositional and structural flexibility allowing for the achievement of high intrinsic electrocatalytic activity. In this review, we summarize the present research progress in the design, development, and application of perovskite oxides for electrocatalytic water splitting. The emphasis is on the innovative synthesis strategies and a deeper understanding of structure–activity relationships through a combination of systematic characterization and theoretical research. Finally, the main challenges and prospects for the further development of more efficient electrocatalysts based on perovskite oxides are proposed. It is expected to give guidance for the development of novel non-noble metal catalysts in electrochemical water splitting.
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4
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Mutschke A, Schulz A, Bertmer M, Ritter C, Karttunen AJ, Kieslich G, Kunkel N. Expanding the hydride chemistry: Antiperovskites A3MO 4H ( A = Rb, Cs; M = Mo, W) introducing the transition oxometalate hydrides. Chem Sci 2022; 13:7773-7779. [PMID: 35865889 PMCID: PMC9258318 DOI: 10.1039/d2sc01861f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/24/2022] [Indexed: 12/03/2022] Open
Abstract
The four compounds A3MO4H (A = Rb, Cs; M = Mo, W) are introduced as the first members of the new material class of the transition oxometalate hydrides. The compounds are accessible via a thermal synthesis route with carefully controlled conditions. Their crystal structures were solved by neutron diffraction of the deuterated analogues. Rb3MoO4D, Cs3MoO4D and Cs3WO4D crystallize in the antiperovskite-like K3SO4F-structure type, while Rb3WO4D adopts a different orthorhombic structure. 2H MAS NMR, Raman spectroscopy and elemental analysis prove the abundance of hydride ions next to oxometalate ions and experimental findings are supported by quantum chemical calculations. The tetragonal phases are direct and wide band gap semiconductors arising from hydride states, whereas Rb3WO4H shows a unique, peculiar valence band structure dominated by hydride states. The synthesis, structures and electronic properties of the first four heteroanionic compounds containing both hydride and transition oxometalate ions are reported.![]()
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Affiliation(s)
- Alexander Mutschke
- Chair of Inorganic Chemistry with Focus on Novel Materials, Technical University of Munich Lichtenbergstrasse 4 85748 Garching Germany
| | - Annika Schulz
- Chair of Inorganic Chemistry with Focus on Novel Materials, Technical University of Munich Lichtenbergstrasse 4 85748 Garching Germany
| | - Marko Bertmer
- Felix Bloch Institute for Solid State Physics Leipzig University Linnéstrasse 5 04103 Leipzig Germany
| | - Clemens Ritter
- Institut Laue-Langevin 71 Avenue des Martyrs 38042 Grenoble Cedex 9 France
| | - Antti J Karttunen
- Department of Chemistry and Materials Science, Aalto University P.O. Box 16100 FI-00076 Aalto Finland
| | - Gregor Kieslich
- Chair of Inorganic and Metal-Organic Chemistry, Technical University of Munich Lichtenbergstrasse 4 85748 Garching Germany
| | - Nathalie Kunkel
- Chair of Inorganic Chemistry with Focus on Novel Materials, Technical University of Munich Lichtenbergstrasse 4 85748 Garching Germany
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5
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Miyazaki K, Ochi M, Nishikubo T, Suzuki J, Saito T, Kamiyama T, Kuroki K, Yamamoto T, Azuma M. High-Pressure and High-Temperature Synthesis of Anion-Disordered Vanadium Perovskite Oxyhydrides. Inorg Chem 2021; 60:15751-15758. [PMID: 34613695 DOI: 10.1021/acs.inorgchem.1c02399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crystallographic order-disorder phenomena in solid state compounds are of fundamental interest due to intimate relationship between the structure and properties. Here, by using high-pressure and high-temperature synthesis, we obtained vanadium perovskite oxyhydrides Sr1-xNaxVO3-yHy (x = 0, 0.05, 0.1, 0.2) with an anion-disordered structure, which is different from anion-ordered SrVO2H synthesized by topochemical reduction. High-pressure and high-temperature synthesis from nominal composition SrVO2H yielded the anion-disordered perovskite SrVO3-yHy (y ∼ 0.4) with a significant amount of byproducts, while Na substitution resulted in the almost pure anion-disordered perovskite Sr1-xNaxVO3-yHy with an increased amount of hydride anion (y ∼ 0.7 for x = 0.2). The obtained disordered phases for x = 0.1 and 0.2 are paramagnetic with almost temperature-independent electronic conductivity, whereas anion-ordered SrVO2H is an antiferromagnetic insulator. Although we obtained the anion-disordered perovskite under high pressure, a first-principles calculation revealed that the application of pressure stabilizes the ordered phase due to a reduced volume in the ordered structure, suggesting that a further increase of the pressure or reduction of the reaction temperature leads to the anion ordering. This study shows that anion ordering in oxyhydrides can be controlled by changing synthetic pressure and temperature.
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Affiliation(s)
- Kazumasa Miyazaki
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
| | - Masayuki Ochi
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Takumi Nishikubo
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
| | - Jinya Suzuki
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
| | - Takashi Saito
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tokai, Ibaraki 319-1106, Japan
| | - Takashi Kamiyama
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tokai, Ibaraki 319-1106, Japan
| | - Kazuhiko Kuroki
- Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Takafumi Yamamoto
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
| | - Masaki Azuma
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan.,Kanagawa Institute of Industrial Science and Technology, 705-1 Shimoimaizumi, Ebina 243-0435, Japan
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6
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Higashi K, Ochi M, Nambu Y, Yamamoto T, Murakami T, Yamashina N, Tassel C, Matsumoto Y, Takatsu H, Brown CM, Kageyama H. Enhanced Magnetic Interaction by Face-Shared Hydride Anions in 6H-BaCrO 2H. Inorg Chem 2021; 60:11957-11963. [PMID: 34309363 DOI: 10.1021/acs.inorgchem.1c00992] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Studies on magnetic oxyhydrides have been almost limited to perovskite-based lattices with corner-sharing octahedra with a M-H-M (M: transition metal) angle of θ ∼ 180°. Using a high-pressure method, we prepared BaCrO2H with a 6H-type hexagonal perovskite structure with corner- and face-sharing octahedra, offering a unique opportunity to investigate magnetic interactions based on a θ ∼ 90° case. Neutron diffraction for BaCrO2H revealed an antiferromagnetic (AFM) order at TN ∼ 375 K, which is higher than ∼240 K in BaCrO3-xFx. The relatively high TN of BaCrO2H can be explained by the preferred occupancy of H- at the face-sharing site that provides AFM superexchange in addition to AFM direct exchange interactions. First-principles calculations on BaCrO2H in comparison with BaCrO2F and BaMnO3 further reveal that the direct Cr-Cr interaction is significantly enhanced by shortening the Cr-Cr distance due to the covalent nature of H-. This study provides a useful strategy for the extensive control of magnetic interactions by exploiting the difference in the covalency of multiple anions.
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Affiliation(s)
- Kentaro Higashi
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Masayuki Ochi
- Department of Physics, Osaka University, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Yusuke Nambu
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.,FOREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.,Japan Organization for Advanced Studies, Tohoku University, Sendai 980-8577, Japan
| | - Takafumi Yamamoto
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Taito Murakami
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Naoya Yamashina
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Cédric Tassel
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Yuki Matsumoto
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Hiroshi Takatsu
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Craig M Brown
- Center for Neutron Research, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Hiroshi Kageyama
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
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7
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López-Paz SA, Nakano K, Sanchez-Marcos J, Tassel C, Alario-Franco MA, Kageyama H. Hydride-Reduced Eu 2SrFe 2O 6: A T-to-T' Conversion Enabling Fe 2+ in Square-Planar Coordination. Inorg Chem 2020; 59:12913-12919. [PMID: 32811139 DOI: 10.1021/acs.inorgchem.0c01982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Low-temperature reaction of A-site-ordered layered perovskite Eu2SrFe2O7 (T structure) with CaH2 induces a shift in the Eu2O2 slabs to form Eu2SrFe2O6 with a T' structure (I4/mmm space group) in which only the Fe cation is reduced. Contrary to the previously reported T' structures with Jahn-Teller-active d9 cations (Cu2+ and Ni+), stabilization of Eu2SrFe2O6 with the Fe2+ (d6) cation reflects the stability of the FeO4 square-planar unit. The stability of T'-type Eu2SrFe2O6 over a T-type polymorph is confirmed by density functional theory calculations, revealing the dz2 occupancy for the T' structure. Eu2SrFe2O6 has a bilayer magnetic framework with an Fe-O-Fe superexchange J∥ and an Fe-Fe direct exchange J⊥ (where J∥ > J⊥), which broadly explains the observed TN of 390-404 K. Interestingly, the magnetic moments of Eu2SrFe2O6 lie in the ab plane, in contrast to the structurally similar Sr3Fe2O4Cl2 having an out-of-plane spin alignment.
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Affiliation(s)
- Sara A López-Paz
- Departamento Química Inorgánica, Universidad Complutense de Madrid, Avenida Complutense s/n 28045, Madrid 28049, Spain.,Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - K Nakano
- Japan Advanced Institute of Science and Technology (JAIST), Asahidai 1-1, Nomi, Ishikawa 923-1292, Japan
| | - J Sanchez-Marcos
- Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, c/Francisco Tomás y Valiente 7, Madrid 28049, Spain)
| | - C Tassel
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - M A Alario-Franco
- Departamento Química Inorgánica, Universidad Complutense de Madrid, Avenida Complutense s/n 28045, Madrid 28049, Spain
| | - H Kageyama
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
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8
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Structural, magnetic and electronic properties of EuTi0.5W0.5O3-xNx perovskite oxynitrides. J SOLID STATE CHEM 2020. [DOI: 10.1016/j.jssc.2020.121274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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10
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Gui Z, Janotti A. Carrier-Density-Induced Ferromagnetism in EuTiO_{3} Bulk and Heterostructures. PHYSICAL REVIEW LETTERS 2019; 123:127201. [PMID: 31633976 DOI: 10.1103/physrevlett.123.127201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Indexed: 06/10/2023]
Abstract
EuTiO_{3} is an antiferromagnetic (AFM) material showing strong spin-lattice interactions, large magnetoelectric response, and quantum paraelectric behavior at low temperatures. Using electronic-structure calculations, we show that adding electrons to the conduction band leads to ferromagnetism. The transition from antiferromagnetism to ferromagnetism is predicted to occur at ∼0.08 electrons/Eu (∼1.4×10^{21} cm^{-3}). This effect is also predicted to occur in heterostructures such as LaAlO_{3}/EuTiO_{3}, where ferromagnetism is triggered by the formation of a high-density two-dimensional electron gas in the EuTiO_{3}. Our analysis indicates that the coupling between Ti 3d and Eu 5d plays a crucial role in lowering the Ti 3d conduction band in the ferromagnetic (FM) phase, leading to an almost linear dependence of the energy difference between the FM and AFM ordering on the carrier concentration. These findings open up possibilities in designing field-effect transistors using EuTiO_{3}-based heterointerfaces to probe fundamental interactions between highly localized spins and itinerant, polarized charge carriers.
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Affiliation(s)
- Zhigang Gui
- Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
| | - Anderson Janotti
- Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
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11
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Kageyama H, Yajima T, Tsujimoto Y, Yamamoto T, Tassel C, Kobayashi Y. Exploring Structures and Properties through Anion Chemistry. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2019. [DOI: 10.1246/bcsj.20190095] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Hiroshi Kageyama
- Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8581, Japan
| | - Takeshi Yajima
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Yoshihiro Tsujimoto
- Research Centre for Functional Materials, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Takafumi Yamamoto
- Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8581, Japan
| | - Cedric Tassel
- Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8581, Japan
| | - Yoji Kobayashi
- Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8581, Japan
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12
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Takeiri F, Watanabe A, Kuwabara A, Nawaz H, Ayu NIP, Yonemura M, Kanno R, Kobayashi G. Ba 2ScHO 3: H - Conductive Layered Oxyhydride with H - Site Selectivity. Inorg Chem 2019; 58:4431-4436. [PMID: 30784265 DOI: 10.1021/acs.inorgchem.8b03593] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hydride (H-) conduction is a new frontier related to hydrogen transport in solids. Here, a new H- conductive oxyhydride Ba2ScHO3 was successfully synthesized using a high-pressure technique. Powder X-ray and neutron diffraction experiments investigated the fact that Ba2ScHO3 adopts a K2NiF4-type structure with H- ions preferentially occupying the apical sites, as supported by theoretical calculations. Electrochemical impedance spectra showed that Ba2ScHO3 exhibited H- conduction and a conductivity of 5.2 × 10-6 S cm-1 at 300 °C. This value is much higher than that of BaScO2H, which has an ideal perovskite structure, suggesting the advantage of layered structures for H- conduction. Tuning site selectivity of H- ions in layered oxyhydrides might be a promising strategy for designing fast H- conductors applicable for novel electrochemical devices.
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Affiliation(s)
- Fumitaka Takeiri
- Department of Materials Molecular Science , Institute for Molecular Science , 38 Nishigonaka, Myodaiji , Okazaki , Aichi 444-8585 , Japan.,SOKENDAI (The Graduate University for Advanced Studies) , 38 Nishigonaka, Myodaiji , Okazaki , Aichi 444-8585 , Japan
| | - Akihiro Watanabe
- Department of Materials Molecular Science , Institute for Molecular Science , 38 Nishigonaka, Myodaiji , Okazaki , Aichi 444-8585 , Japan.,Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering , Tokyo Institute of Technology , 4259 Nagatsuta , Midori , Yokohama 226-8502 , Japan
| | - Akihide Kuwabara
- Nanostructures Research Laboratory , Japan Fine Ceramics Center , 2-4-1 Mutsuno , Atsuta , Nagoya 456-8587 , Japan
| | - Haq Nawaz
- Department of Materials Molecular Science , Institute for Molecular Science , 38 Nishigonaka, Myodaiji , Okazaki , Aichi 444-8585 , Japan.,SOKENDAI (The Graduate University for Advanced Studies) , 38 Nishigonaka, Myodaiji , Okazaki , Aichi 444-8585 , Japan
| | - Nur Ika Puji Ayu
- Neutron Science Laboratory (KENS), Institute of Materials Structure Science , High Energy Accelerator Research Organization (KEK) , 203-1 Shirakata , Tokai , Ibaraki 319-1106 , Japan
| | - Masao Yonemura
- Neutron Science Laboratory (KENS), Institute of Materials Structure Science , High Energy Accelerator Research Organization (KEK) , 203-1 Shirakata , Tokai , Ibaraki 319-1106 , Japan
| | - Ryoji Kanno
- All-Solid-State Battery Unit, Institute of Innovative Research , Tokyo Institute of Technology , 4259 Nagatsuta , Midori , Yokohama 226-8502 , Japan
| | - Genki Kobayashi
- Department of Materials Molecular Science , Institute for Molecular Science , 38 Nishigonaka, Myodaiji , Okazaki , Aichi 444-8585 , Japan.,SOKENDAI (The Graduate University for Advanced Studies) , 38 Nishigonaka, Myodaiji , Okazaki , Aichi 444-8585 , Japan
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13
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Nedumkandathil R, Jaworski A, Grins J, Bernin D, Karlsson M, Eklöf-Österberg C, Neagu A, Tai CW, Pell AJ, Häussermann U. Hydride Reduction of BaTiO 3 - Oxyhydride Versus O Vacancy Formation. ACS OMEGA 2018; 3:11426-11438. [PMID: 31459246 PMCID: PMC6645482 DOI: 10.1021/acsomega.8b01368] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/29/2018] [Indexed: 06/09/2023]
Abstract
We investigated the hydride reduction of tetragonal BaTiO3 using the metal hydrides CaH2, NaH, MgH2, NaBH4, and NaAlH4. The reactions employed molar BaTiO3/H ratios of up to 1.8 and temperatures near 600 °C. The air-stable reduced products were characterized by powder X-ray diffraction (PXRD), transmission electron microscopy, thermogravimetric analysis (TGA), and 1H magic angle spinning (MAS) NMR spectroscopy. PXRD showed the formation of cubic products-indicative of the formation of BaTiO3-x H x -except for NaH. Lattice parameters were in a range between 4.005 Å (for NaBH4-reduced samples) and 4.033 Å (for MgH2-reduced samples). With increasing H/BaTiO3 ratio, CaH2-, NaAlH4-, and MgH2-reduced samples were afforded as two-phase mixtures. TGA in air flow showed significant weight increases of up to 3.5% for reduced BaTiO3, suggesting that metal hydride reduction yielded oxyhydrides BaTiO3-x H x with x values larger than 0.5. 1H MAS NMR spectroscopy, however, revealed rather low concentrations of H and thus a simultaneous presence of O vacancies in reduced BaTiO3. It has to be concluded that hydride reduction of BaTiO3 yields complex disordered materials BaTiO3-x H y □(x-y) with x up to 0.6 and y in a range 0.04-0.25, rather than homogeneous solid solutions BaTiO3-x H x . Resonances of (hydridic) H substituting O in the cubic perovskite structure appear in the -2 to -60 ppm spectral region. The large range of negative chemical shifts and breadth of the signals signifies metallic conductivity and structural disorder in BaTiO3-x H y □(x-y). Sintering of BaTiO3-x H y □(x-y) in a gaseous H2 atmosphere resulted in more ordered materials, as indicated by considerably sharper 1H resonances.
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Affiliation(s)
- Reji Nedumkandathil
- Department
of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden
| | - Aleksander Jaworski
- Department
of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden
| | - Jekabs Grins
- Department
of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden
| | - Diana Bernin
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, SE-41296 Gothenburg, Sweden
| | - Maths Karlsson
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, SE-41296 Gothenburg, Sweden
| | - Carin Eklöf-Österberg
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, SE-41296 Gothenburg, Sweden
| | - Alexandra Neagu
- Department
of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden
| | - Cheuk-Wai Tai
- Department
of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden
| | - Andrew J. Pell
- Department
of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden
| | - Ulrich Häussermann
- Department
of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden
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14
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Hernandez OJ, Geneste G, Yajima T, Kobayashi Y, Okura M, Aidzu K, Tassel C, Paofai S, Swain D, Ritter C, Kageyama H. Site Selectivity of Hydride in Early-Transition-Metal Ruddlesden–Popper Oxyhydrides. Inorg Chem 2018; 57:11058-11067. [DOI: 10.1021/acs.inorgchem.8b01645] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Olivier J. Hernandez
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France
| | | | - Takeshi Yajima
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yoji Kobayashi
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Masatoshi Okura
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kouhei Aidzu
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Cédric Tassel
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Serge Paofai
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France
| | - Diptikanta Swain
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Clemens Ritter
- Institut Laue-Langevin, 71 avenue des Martyrs CS 20156, 38042 Grenoble Cedex 9, France
| | - Hiroshi Kageyama
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
- CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
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15
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Suppression of H–/O2– exchange by incorporated nitride anions in the perovskite lattice. J SOLID STATE CHEM 2017. [DOI: 10.1016/j.jssc.2017.08.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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16
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Takeiri F, Aidzu K, Yajima T, Matsui T, Yamamoto T, Kobayashi Y, Hester J, Kageyama H. Promoted Hydride/Oxide Exchange in SrTiO3 by Introduction of Anion Vacancy via Aliovalent Cation Substitution. Inorg Chem 2017; 56:13035-13040. [DOI: 10.1021/acs.inorgchem.7b01845] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Fumitaka Takeiri
- Department of Energy
and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kohei Aidzu
- Department of Energy
and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Takeshi Yajima
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Toshiaki Matsui
- Department of Energy
and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Takafumi Yamamoto
- Department of Energy
and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Yoji Kobayashi
- Department of Energy
and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - James Hester
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Hiroshi Kageyama
- Department of Energy
and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
- CREST, Japan Science and Technology Agency, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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17
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Goto Y, Tassel C, Noda Y, Hernandez O, Pickard CJ, Green MA, Sakaebe H, Taguchi N, Uchimoto Y, Kobayashi Y, Kageyama H. Pressure-Stabilized Cubic Perovskite Oxyhydride BaScO 2H. Inorg Chem 2017; 56:4840-4845. [PMID: 28398729 DOI: 10.1021/acs.inorgchem.6b02834] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We report a scandium oxyhydride BaScO2H prepared by solid state reaction under high pressure. Rietveld refinements against powder synchrotron X-ray and neutron diffraction data revealed that BaScO2H adopts the ideal cubic perovskite structure (Pm3̅m), where oxide (O2-) and hydride (H-) anions are disordered. 1H nuclear magnetic resonance (NMR) spectroscopy provides a positive chemical shift of about +4.4 ppm, which can be understood by the distance to the nearest (and possibly the next nearest) cation from the H nucleus. A further analysis of the NMR data and calculations based on ab initio random structure searches suggest a partial cis preference in ScO4H2 octahedra. The present oxyhydride, if compositionally or structurally tuned, may become a candidate for H- conductors.
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Affiliation(s)
- Yoshihiro Goto
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University , Kyoto 615-8510, Japan
| | - Cédric Tassel
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University , Kyoto 615-8510, Japan
| | - Yasuto Noda
- Division of Chemistry, Graduate School of Science, Kyoto University , Kyoto 606-8502, Japan
| | - Olivier Hernandez
- Institut des Sciences Chimiques de Rennes, UMR CNRS 6226, Université de Rennes 1 , Bâtiment 10B, Campus de Beaulieu, Rennes F-35042, France
| | - Chris J Pickard
- Department of Materials Science & Metallurgy, University of Cambridge , 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom.,Advanced Institute for Materials Research (AIMR), Tohoku University , 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Mark A Green
- School of Physical Sciences, University of Kent , Canterbury CT2 7NR, United Kingdom
| | - Hikari Sakaebe
- National Institute of Advanced Industrial Science and Technology (AIST) , Ikeda, Osaka 563-8577, Japan
| | - Noboru Taguchi
- National Institute of Advanced Industrial Science and Technology (AIST) , Ikeda, Osaka 563-8577, Japan
| | - Yoshiharu Uchimoto
- Graduate School of Human and Environmental Studies, Kyoto University , Kyoto 606-8501, Japan
| | - Yoji Kobayashi
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University , Kyoto 615-8510, Japan
| | - Hiroshi Kageyama
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University , Kyoto 615-8510, Japan
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18
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Kobayashi Y, Hernandez O, Tassel C, Kageyama H. New chemistry of transition metal oxyhydrides. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2017; 18:905-918. [PMID: 29383042 PMCID: PMC5784496 DOI: 10.1080/14686996.2017.1394776] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 10/16/2017] [Accepted: 10/17/2017] [Indexed: 05/06/2023]
Abstract
In this review we describe recent advances in transition metal oxyhydride chemistry obtained by topochemical routes, such as low temperature reduction with metal hydrides, or high-pressure solid-state reactions. Besides the crystal chemistry, magnetic and transport properties of the bulk powder and epitaxial thin film samples, the remarkable lability of the hydride anion is particularly highlighted as a new strategy to discover unprecedented mixed anion materials.
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Affiliation(s)
- Yoji Kobayashi
- Department of Energy & Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
- Corresponding author.
| | - Olivier Hernandez
- Solid State Chemistry and Materials Group, Institute of Chemical Sciences at Rennes, UMR 6226 CNRS-University of Rennes 1, Rennes, France
| | - Cédric Tassel
- Department of Energy & Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Hiroshi Kageyama
- Department of Energy & Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
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19
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Oka D, Fukumura T. Crystal engineering for novel functionalities with oxide thin film epitaxy. CrystEngComm 2017. [DOI: 10.1039/c7ce00322f] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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20
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Kususe Y, Yoshida S, Fujita K, Akamatsu H, Fukuzumi M, Murai S, Tanaka K. Structural phase transitions in EuNbO3 perovskite. J SOLID STATE CHEM 2016. [DOI: 10.1016/j.jssc.2016.04.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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21
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Liu BM, Zhang ZG, Zhang K, Kuroiwa Y, Moriyoshi C, Yu HM, Li C, Zheng LR, Li LN, Yang G, Zhou Y, Fang YZ, Hou JS, Matsushita Y, Sun HT. Unconventional Luminescent Centers in Metastable Phases Created by Topochemical Reduction Reactions. Angew Chem Int Ed Engl 2016; 55:4967-71. [DOI: 10.1002/anie.201601191] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Bo-Mei Liu
- College of Chemistry; Chemical Engineering and Materials Science, Soochow University; Suzhou 215123 P.R. China
| | - Zhi-Gang Zhang
- Department of Physical Science; Hiroshima University; Higashihiroshima Hiroshima 739-8526 Japan
| | - Kai Zhang
- School of Materials Science and Engineering; Shanghai Institute of Technology; Shanghai 201418 P.R. China
| | - Yoshihiro Kuroiwa
- Department of Physical Science; Hiroshima University; Higashihiroshima Hiroshima 739-8526 Japan
| | - Chikako Moriyoshi
- Department of Physical Science; Hiroshima University; Higashihiroshima Hiroshima 739-8526 Japan
| | - Hui-Mei Yu
- Shanghai Institute of Ceramics; Chinese Academy of Sciences; Shanghai 200050 P.R. China
| | - Chao Li
- Electronic Materials Research Laboratory; Key Laboratory of the Ministry of Education and International Center for Dielectric Research; Xi'an Jiaotong University; Xi'an 710049 P.R. China
| | - Li-Rong Zheng
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics; Chinese Academy of Sciences; Beijing 100049 P.R. China
| | - Li-Na Li
- Shanghai Synchrotron Radiation Facility; Shanghai Institute of Applied Physics; Chinese Academy of Sciences; Shanghai 201204 P.R. China
| | - Guang Yang
- Electronic Materials Research Laboratory; Key Laboratory of the Ministry of Education and International Center for Dielectric Research; Xi'an Jiaotong University; Xi'an 710049 P.R. China
| | - Yang Zhou
- College of Chemistry; Chemical Engineering and Materials Science, Soochow University; Suzhou 215123 P.R. China
| | - Yong-Zheng Fang
- School of Materials Science and Engineering; Shanghai Institute of Technology; Shanghai 201418 P.R. China
| | - Jing-Shan Hou
- School of Materials Science and Engineering; Shanghai Institute of Technology; Shanghai 201418 P.R. China
| | - Yoshitaka Matsushita
- National Institute for Material Sciences (NIMS); 1-2-1 Sengen, Tsukuba-city Ibaraki 305-0047 Japan
| | - Hong-Tao Sun
- College of Chemistry; Chemical Engineering and Materials Science, Soochow University; Suzhou 215123 P.R. China
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22
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Unconventional Luminescent Centers in Metastable Phases Created by Topochemical Reduction Reactions. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201601191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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23
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Mikita R, Aharen T, Yamamoto T, Takeiri F, Ya T, Yoshimune W, Fujita K, Yoshida S, Tanaka K, Batuk D, Abakumov AM, Brown CM, Kobayashi Y, Kageyama H. Topochemical Nitridation with Anion Vacancy-Assisted N3–/O2– Exchange. J Am Chem Soc 2016; 138:3211-7. [DOI: 10.1021/jacs.6b00088] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Dmitry Batuk
- Electron
Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - Artem M. Abakumov
- Electron
Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
- Skoltech
Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, 143026 Moscow, Russia
| | - Craig M. Brown
- Center
for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States
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24
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Orbital Delocalization and Enhancement of Magnetic Interactions in Perovskite Oxyhydrides. Sci Rep 2016; 6:19653. [PMID: 26804825 PMCID: PMC4726173 DOI: 10.1038/srep19653] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/16/2015] [Indexed: 11/10/2022] Open
Abstract
Recent experiments showed that some perovskite oxyhydrides have surprisingly high magnetic-transition temperature. In order to unveil the origin of this interesting phenomenon, we investigate the magnetism in SrCrO2H and SrVO2H on the basis of first-principles calculations and Monte Carlo simulations. Our work indicates that the Cr-O-Cr superexchange interaction in SrCrO2H is unexpectedly strong. Different from the previous explanation in terms of the H− ion substitution induced increase of the Cr-O-Cr bond angle, we reveal instead that this is mainly because the 3d orbitals in perovskite oxyhydrides becomes more delocalized since H− ions have weaker electronegativity and less electrons than O2− ions. The delocalized 3d orbitals result in stronger Cr-O interactions and enhance the magnetic-transition temperature. This novel mechanism is also applicable to the case of SrVO2H. Furthermore, we predict that SrFeO2H will have unprecedented high Neel temperature because of the extraordinarily strong Fe-H-Fe σ-type interactions. Our work suggests the anion substitution can be used to effectively manipulate the magnetic properties of perovskite compounds.
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25
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Jiang K, Zhao R, Zhang P, Deng Q, Zhang J, Li W, Hu Z, Yang H, Chu J. Strain and temperature dependent absorption spectra studies for identifying the phase structure and band gap of EuTiO3 perovskite films. Phys Chem Chem Phys 2015; 17:31618-23. [PMID: 26568432 DOI: 10.1039/c5cp06318c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Post-annealing has been approved to effectively relax the out-of-plane strain in thin films. Epitaxial EuTiO3 (ETO) thin films, with and without strain, have been fabricated on (001) LaAlO3 substrates by pulsed laser deposition. The absorption and electronic transitions of the ETO thin films are investigated by means of temperature dependent transmittance spectra. The antiferrodistortive phase transition can be found at about 260-280 K. The first-principles calculations indicate there are two interband electronic transitions in ETO films. Remarkably, the direct optical band gap and higher interband transition for ETO films show variation in trends with different strains and temperatures. The strain leads to a band gap shrinkage of about 240 meV while the higher interband transition an expansion of about 140 meV. The hardening of the interband transition energies in ETO films with increasing temperature can be attributed to the Fröhlich electron-phonon interaction. The behavior can be linked to the strain and low temperature modified valence electronic structure, which is associated with rotations of the TiO6 octahedra.
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Affiliation(s)
- Kai Jiang
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241, China.
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