A5049458565- Iron-based superconductors research
- Ammonia Synthesis and Nitrogen Reduction
- Corporate Taxation and Avoidance
- Rare-earth and actinide compounds
- Luminescence Properties of Advanced Materials
- Inorganic Chemistry and Materials
- Catalytic Processes in Materials Science
- Intellectual Capital and Performance Analysis
- Physics of Superconductivity and Magnetism
- Hydrogen Storage and Materials
- Chemical Synthesis and Characterization
- Muon and positron interactions and applications
- Advanced Condensed Matter Physics
- Glass properties and applications
- Advanced Photocatalysis Techniques
- Nanomaterials for catalytic reactions
- Magnetic and transport properties of perovskites and related materials
- Superconductivity in MgB2 and Alloys
- Solid-state spectroscopy and crystallography
- ZnO doping and properties
- Perovskite Materials and Applications
- X-ray Diffraction in Crystallography
- Copper-based nanomaterials and applications
- Topological Materials and Phenomena
- Zeolite Catalysis and Synthesis
National Institute for Materials Science
2023-2025
Tokyo Institute of Technology
2014-2023
Materials Research Center
2014-2020
High Energy Accelerator Research Organization
2019-2020
The Graduate University for Advanced Studies, SOKENDAI
2019
Kyoto University
2017
Japan Science and Technology Agency
2002-2016
Japan Atomic Energy Agency
2013
Bhabha Atomic Research Centre
2010-2011
Forschungszentrum Jülich
2010-2011
We removed approximately 100% of clathrated oxygen ions from the crystallographic cages in a single crystal 12CaO.7Al2O3, leading to formation high-density (approximately 2 x 10(21) cm-3) electrons highly localized cages. The resulting electron forms structure that we interpret as an F+ center and migrates throughout by hopping neighboring cage with conductivity 100 siemens per centimeter, demonstrating encaged behaves anion. anions couple antiferromagnetically each other, forming...
Ruthenium-loaded metal hydrides with hydrogen vacancies function as efficient catalysts for ammonia synthesis under low temperature and pressure conditions.
Iron arsenide superconductors based on the material LaFeAsO(1-x)F(x) are characterized by a two-dimensional Fermi surface (FS) consisting of hole and electron pockets yielding structural antiferromagnetic transitions at x=0. Electron doping substituting O(2-) with F(-) suppresses these gives rise to superconductivity maximum T(c) 26 K x=0.1. However, over-doped region cannot be accessed due poor solubility above x=0.2. Here we overcome this problem LaFeAsO hydrogen. We report phase diagram...
Mixed anionic materials such as oxyhydrides and oxynitrides have recently attracted significant attention due to their unique properties, fast hydride ion conduction, enhanced ferroelectrics, catalytic activity. However, high temperature (≥800 °C) and/or complicated processes are required for the synthesis of these compounds. Here we report that a novel perovskite oxynitride-hydride, BaCeO3-xNyHz, can be directly synthesized by reaction CeO2 with Ba(NH2)2 at low temperatures (300-600 °C)....
We report a metallic state in nanostructured porous crystal 12CaO x 7Al2O3 by incorporating electrons the inherent subnanometer-sized cages, which three-dimensionally closely packed cage structure acts as an electronic conduction path. High-density electron doping ( approximately 2 10(21) cm(-3)), was achieved thermal treatment Ti metal vapor at 1100 degrees C, induces homogenization of geometry to symmetric state, resulting insulator-metal transition with sharp enhancement drift mobility...
Extremely high concentrations (>1020 cm-3) of active oxygenic radicals, O- and O2-, have been created in the zeolitic crystal, 12CaO.7Al2O3 (C12A7), which can accommodate anions its cavities. An increase oxygen pressure a decrease water vapor at temperature enhance formation radicals. The oxidation Pt is observed on surface material as result reaction with oxygens.
A new quaternary fluoroarsenide CaFeAsF with the tetragonal ZrCuSiAs-type structure composed of alternate stacking (FeAs)delta- and (CaF)delta+ layers was synthesized. is a poor metal shows anomaly at approximately 120 K in temperature dependence electrical conductivity. The electron doping by partial replacement iron cobalt suppresses induces bulk superconductivity (optimal Tc = 22 for CaFe0.9Co0.1AsF), analogous to recently discovered FeAs-based superconductors. present results suggest...
[Ca 24 Al 28 O 64 ] 4+ (4e – ) is a new inorganic electride, which air‐stable even at ∼ 300 °C. Its electron field‐emission properties originate from anions encaged in subnanometer‐sized cages embedded its crystal structure, and the emission current controlled by Fowler–Nordheim field high electric fields (see Figure). Field‐emission display devices demonstrate bright light clearly visible under ambient (inset).
Electrides are ionic crystals in which the anionic electrons confined to interstitial subnanometer-sized spaces. At present, reported electrides only consist of main-group elements. Here, we report a layered-structure transition-metal hypocarbide electride, Y2C, with quasi-two-dimensional (quasi-2D) interlayer space. Physical properties measurements reveal polycrystalline Y2C exhibits semimetallic behavior, and paramagnetism an effective magnetic moment ∼0.6 μB/Y, because existence localized...
Hydrogen is an impurity species having important role in the physical properties of semiconductors. Despite numerous studies, hydrogen oxide semiconductors remains unsolved puzzle. This situation arises from insufficient information about chemical state hydrogen. Here, we report direct evidence for anionic hydrogens bonding to metal cations amorphous In–Ga–Zn–O (a-IGZO) thin films thin-film transistors (TFT) applications and discuss how impurities affect electronic structure a-IGZO. Infrared...
High-throughput ab initio screening of approximately 34000 materials in the Materials Project was conducted to identify two-dimensional (2D) electride materials, which are composed cationic layers and anionic electrons confined a 2D empty space. The based on three indicators: (1) positive total formal charge per formula unit; (2) layered structures for two-dimensionality; (3) spaces between layer units. Three nitrides, Ca2N, Sr2N, Ba2N, carbide Y2C were identified as electrides, where Ca2N...
Utilizing the high stability of calcium and rare-earth hydrides, CaFeAsF${}_{1\ensuremath{-}x}$H${}_{x}$ ($x$ $=$ 0.0--1.0) SmFeAsO${}_{1\ensuremath{-}x}$H${}_{x}$ 0.0--0.47) have been synthesized using pressure to form hydrogen-substituted 1111-type iron-arsenide superconductors. Neutron diffraction density functional calculations demonstrated that hydrogens are incorporated as H${}^{\ensuremath{-}}$ ions occupying F${}^{\ensuremath{-}}$ sites in blocking layer CaFeAsF. The resulting is...
Abstract Mixed-anion compounds, in which multiple anions such as O2−, N3−, and H− are contained the same compound, have recently attracted attention. Because mixed-anion compounds a unique crystal structure with coordinated to cations, materials fundamentally new innovative functions expected be developed for various chemistry physics applications, including catalysts, batteries, superconductors. In this Account, recent progress development of by MEXT project is described, emphasis on...
We report on high-pressure powder synchrotron x-ray diffraction studies $M$Fe${}_{2}$As${}_{2}$ ($M$$=$Ba, Ca) over a range of temperatures and pressures up to about 56 GPa using membrane diamond-anvil cell. Our data indicate phase transition collapsed tetragonal in both compounds upon compression. The at 300 K are measured pressure-increasing -decreasing cycles. measurements show that the Ba compound, occurs 27 GPa, which is much higher than pressure 1.7 Ca compound. At low temperature, we...
Wide bandgap conductors such as In₂O₃ and ZnO are used transparent conducting oxides (TCOs). To date, TCOs realized using post transition metal cations with largely spread s-orbitals In³⁺, Sn⁴⁺, Zn²⁺ Cd²⁺. On the other hand, no good electronic conductor has been in of Al, Si Ge. Here we report conversion an oxide Ge into a by employing concept superdegeneracy. We find that cubic SrGeO₃, synthesized under high pressure, displays direct 3.5 eV, carrier mobility 12 cm²(Vs)⁻¹, conductivities 3...
Recent discoveries of topological phases realized in electronic states solids have revealed an important role topology, which ubiquitously appears various materials nature. Many well-known turned out to be materials, and this new viewpoint topology has opened a horizon material science. In paper we find that electrides are suitable for achieving phases, including insulating semimetal phases. the electrides, electrons serve as anions, bands occupied by anionic lie near Fermi level, because...
In view of the strong electron-donating nature H– and extensive vacancy formation in metals by hydrogen insertion, a series LnH2+x (Ln = La, Ce, or Y) compounds with fluorite-type structures were verified to be first hydride-based electride, where itinerant electrons populating cage are surrounded anions. The electron transfer into probably originates from Ln–cage covalent interaction. To best our knowledge, anion-rich electrides extremely rare, key requirement for their is that site not...
2D magnets and their engineered magnetic heterostructures are intriguing materials for both fundamental physics application prospects. On the basis of recently discovered intrinsic topological insulators (MnBi2 Te4 )(Bi2 Te3 )n , here, a new type magnet, in which layers separated by large number non-magnetic become magnetically independent, is proposed. This magnet named as single-layer regarding vanishing interlayer exchange coupling. Theoretical calculations magnetization measurements...
Electrical resistivity under high pressure have been measured on nominally pure SrFe2As2 up to 14 GPa. The drop appeared with increasing pressure, and we clearly observed zero resistivity. maximum of superconducting transition temperature (Tc) is 38 K. value corresponding the one optimally doping AFe2As2 (A=Sr, Ba) system K+ ions at A2+ site.