Yoshihiro Tsujimoto
@nims.go.jp
Research Center for Materials Nanoarchitechtonics
National Institute for Materials Science
RESEARCH INTERESTS
Inorganic solid state chemistry, high-pressure synthesis, low-temperature sysnthesis, flux crystal growth, ionic conductors, nonlinear optics, low-dimensional magnetism
Scopus Publications
Scopus Publications
Naoki Abe, Yuya Hano, Hiroaki Ishizuka, Yusuke Kozuka, Terumasa Tadano, Yoshihiro Tsujimoto, Kazunari Yamaura, Shintaro Ishiwata, and Jun Fujioka
Springer Science and Business Media LLC
AbstractElectrons in metals can show a giant anomalous Hall effect (AHE) when interacting with characteristic spin texture. The AHE has been discussed in terms of scalar-spin-chirality (SSC) in long-range-ordered noncollinear spin textures typified by Skyrmion. The SSC becomes effective even in the paramagnetic state with thermal fluctuations, but the resultant AHE has been limited to be very small. Here, we report the observation of large AHE caused by the spin fluctuation near the devil’s staircase transition in a collinear antiferromagnetic metal SrCo6O11. The AHE is prominent near and above the transition temperature at moderate magnetic fields, where the anomalous Hall angle becomes the highest level among known oxide collinear ferromagnets/antiferromagnets (>2%). Furthermore, the anomalous Hall conductivity is quadratically scaled to the conductivity. These results imply that the thermally induced solitonic spin defects inherent to the devil’s staircase transition promote SSC-induced skew scattering.
Yu Meng, Naoyoshi Nunotani, Kazuki Shitara, Yoshitaka Matsushita, Nobuhito Imanaka, Kazunari Yamaura, and Yoshihiro Tsujimoto
Royal Society of Chemistry (RSC)
La-doped Ca2B5O9Cl exhibits one-dimensional chloride-ion transport defined by the dimensionality of the borate framework. Theoretical calculations indicate an unusual interstitialcy mechanism involving complex association between Cl and La atoms.
Hongbo Yuan, Hong Yan, Yu Meng, Yoshitaka Matsushita, Kazunari Yamaura, and Yoshihiro Tsujimoto
American Chemical Society (ACS)
Single crystals of a new titanium oxysulfide, LiLa3Ti2S3O6, were grown from a KI molten salt. Single-crystal X-ray diffraction analysis revealed that LiLa3Ti2S3O6 crystallizes in the space group Pnma with lattice parameters of a = 11.7319(4) Å, b = 3.94787(14) Å, and c = 20.6885(6) Å. In this structure, the one-dimensional chains of corner-sharing TiO5S octahedra are further corner-linked via equatorial and apical oxygen atoms to form unique corrugated two-dimensional perovskite-type layers in the ab plane with one octahedral thickness. These layers were intervened along the c-axis by the LaS rock-salt layers corrugated concomitantly with the perovskite-type layers, and LiO2S2 tetrahedral chains were located between these two types of two-dimensional layers. LiLa3Ti2S3O6 can be viewed as a modified K2NiF4-type structure with TiO5S octahedral layers stacked in a zigzag manner along the c axis. The oxysulfide has a direct-type band gap of 1.85 eV, based on UV-vis-NIR diffuse reflectance measurements. First-principles calculations showed that the conduction band minimum mainly consists of Ti 3d orbitals, and the valence band maximum consists of S 3p, O 2p, and Li 2s orbitals. The electronic structures near the Fermi level are similar to those of the structurally related photocatalytic oxysulfides Y2Ti2S2O5 and La5Ti2CuS5O7.
Daqin Guan, Hengyue Xu, Yu‐Cheng Huang, Chao Jing, Yoshihiro Tsujimoto, Xiaomin Xu, Zezhou Lin, Jiayi Tang, Zehua Wang, Xiao Sun,et al.
Wiley
AbstractTetrahedral, pyramidal, and octahedral metal‐oxygen coordinated ligands are fundamental components in all metal‐oxide structures. Understanding the impacts of their spatiotemporal behaviors during electrochemical oxidation is crucial for diverse applications, yet remains unsolved due to challenges in designing model oxides and conducting operando characterizations. Herein, combining a suite of advanced operando characterizations and systematic computations, a link between oxygen‐evolving performance and operational structural properties is established on model oxides. Compared with tetrahedral and octahedral structures, pyramidal structure is more susceptible to OH− attack due to its pristine unsaturated and asymmetric features and constant single‐electron occupancy on the active z2 orbital during reaction, leading to surface‐to‐bulk restructuration into active amorphous high‐valence CoOOHx with edge‐sharing configurations. This is accompanied by ion leaching to create nanoscale space, following a leaching tendency of Sr2+ > Ba2+ > La3+ > Y3+. Operando soft X‐ray absorption spectroscopy demonstrates a harder non‐uniform dehydrogenation process over time (Co3+OOH → Co3+/4+OOHx → Co4+OO) because of the enhanced CoO covalency with higher energy barriers. Lattice oxygen participates in active CoOOHx formation but sacrifices stability. To address this activity‐stability trade‐off, an ion‐tuning strategy is proposed to simultaneously enhance both activity and stability in electrode and device.
Xun Kang, Hiroaki Hayashi, Alexei A. Belik, Yoshihiro Tsujimoto, and Kazunari Yamaura
Informa UK Limited
Xun Kang, Ryuta Ishikawa, Alexei A. Belik, Yoshihiro Tsujimoto, Masao Arai, Satoshi Kawata, and Kazunari Yamaura
American Chemical Society (ACS)
In this study, we successfully synthesized the double perovskite oxide Cd2FeReO6 by using a high-temperature and high-pressure method. The crystal structure was confirmed to belong to the P21/n space group, exhibiting approximately 68% ordering of Fe3+ and Re5+ ions at the perovskite B-site with the remaining regions showing antisite disorder. The measured Curie temperature of Cd2FeReO6 was 460 K, slightly lower than expected but still significantly above room temperature. Remarkably, Cd2FeReO6 displayed a remarkable low-field butterfly type tunneling magnetoresistance of -23% (-37% between the lowest and the largest values) at 5 K and 90 kOe, the highest among the A2FeReO6 (A = Ca, Sr, Pb, Ba) family. First-principles calculations provided insight into the origin of this observed magnetoresistance behavior, revealing Cd2FeReO6's half-metallic ferrimagnetic nature. This research extends our understanding of the double perovskite family and emphasizes its potential significance in the domains of spintronics and materials science. The exploration of differing magnetoresistance behaviors between Cd2FeReO6 and Ca2FeReO6, along with the influence of antisite disorder in Cd2FeReO6, opens intriguing avenues for further research.
Xun Kang, Ryuta Ishikawa, Alexei A. Belik, Yoshihiro Tsujimoto, Satoshi Kawata, and Kazunari Yamaura
American Chemical Society (ACS)
Robert D. Smyth, Dmitry Khalyavin, Yoshihiro Tsujimoto, Kazunari Yamaura, and Simon J. Clarke
Elsevier BV
Louis-Béni Mvélé, Shunsuke Sasaki, Philippe Deniard, Yoshihiro Tsujimoto, Etienne Janod, Catherine Guillot-Deudon, Maria Teresa Caldes, Isabelle Braems, Benoit Corraze, Stéphane Jobic,et al.
American Chemical Society (ACS)
Kouta Kazama, Masato Sakano, Kohei Yamagami, Takuo Ohkochi, Kyoko Ishizaka, Terumasa Tadano, Yusuke Kozuka, Hidetoshi Yoshizawa, Yoshihiro Tsujimoto, Kazunari Yamaura,et al.
American Physical Society (APS)
Hong Yan, Kotaro Fujii, Houria Kabbour, Akira Chikamatsu, Yu Meng, Yoshitaka Matsushita, Masatomo Yashima, Kazunari Yamaura, and Yoshihiro Tsujimoto
American Chemical Society (ACS)
Band gap engineering using multiple anions is an established approach to novel photocatalysts that exhibit suitable band gap energies for water splitting and high photocorrosion resistance. However, few studies have been conducted on photocatalysts with polyanions, including polychalcogenide ions. Here, we present a new quaternary gallium oxysulfide with disulfide pairs (S2)2-, La4Ga2S8O3, grown out of a KI molten salt. Single-crystal X-ray diffraction analysis revealed that the oxysulfide crystallizes in the orthorhombic space group Pbcn with lattice constants of a = 18.3330(6) Å, b = 13.0590(5) Å, and c = 5.9022(3) Å. In the crystal structure, the GaS4-based zigzag chains and OLa4-based fluorite-like strips are independently arranged in two dimensions, which alternately stack via the disulfide pairs along the third direction. The oxysulfide is a direct-type semiconductor with a band gap of 2.45 eV. First-principles calculations combined with X-ray photoemission spectroscopy measurements show that S 3p states derived from the disulfide pairs dominate the valence band maximum and conduction band minimum, and these band-edge positions are suitable for the oxidation and reduction of water. Our comprehensive study based on the electronic structure suggests that the disulfide pairs make La4Ga2S8O3 a potential photocatalyst for water splitting under visible-light irradiation.
Xun Kang, Alexei A. Belik, Yoshihiro Tsujimoto, and Kazunari Yamaura
American Chemical Society (ACS)
Under high-pressure and high-temperature conditions, doped Bi3Re3O11 and Bi3Os3O11 with Fe up to 29 atomic % were synthesized. The crystal structures and chemical compositions of Bi3Os2.45Fe0.55O11 and Bi3Re2.13Fe0.87O11 were determined by synchrotron powder X-ray diffraction and electron probe microanalysis. Both crystal structures were explained by a KSbO3-type model with the space group Pn3̅. Magnetic and electronic transport property measurements showed that Bi3Os2.45Fe0.55O11 exhibited a ferrimagnetic transition at the highest magnetic ordering temperature of 490 K in the KSbO3-type, while Bi3Re2.13Fe0.87O11 exhibited a spin glassy behavior below 22 K. The magnetoresistance at 5 K and 90 kOe was almost zero for Bi3Os2.45Fe0.55O11, but -10% for Bi3Re2.13Fe0.87O11. These results suggest that KSbO3- type 5d oxides, which exhibit only weak temperature-dependent paramagnetism to date, are a group of compounds that can be converted into spintronic materials by doping with 3d elements, leading to the development of new KSbO3-type materials with both theoretical and practical significance.
Jie Chen, Yoshihiro Tsujimoto, Alexei A. Belik, Kazunari Yamaura, and Yoshitaka Matsushita
International Union of Crystallography (IUCr)
The crystal structure of the cubic double-perovskite Sr2Cr0.84Ni0.09Os1.07O6, grown at high pressure, was solved using intensity data measured at 113 K. The Os site was modelled with a partial Ni occupancy, and the Cr site was modelled with both Os and Ni partial occupancy. The refined structure shows that this cubic form is stable at 113 K.
Yoshihiro Tsujimoto, Jun Sugiyama, Masayuki Ochi, Kazuhiko Kuroki, Pascal Manuel, Dmitry D. Khalyavin, Izumi Umegaki, Martin Månsson, Daniel Andreica, Shigeo Hara,et al.
American Physical Society (APS)
Yu Su, Yuki Iwasa, Takayuki Yanagida, Yoshihiro Tsujimoto, Shunqin Luo, and Hiraku Ogino
Optica Publishing Group
Herein, we report the synthesis and luminescence properties of Tb-doped layered perovskite oxychloride, Ba3Y2O5Cl2. Similar to Ba3Y2O5Cl2:Eu3+, single-phase Ba3Y2O5Cl2:Tb3+ was successfully synthesized through a solid-state reaction. The luminescence properties were studied and compared with those of Y2O3:Tb3+. There was only one excitation peak due to the 4f-5d transition of Tb3+, which was different from that of Y2O3:Tb3+ that comprises two peaks. Green emissions from Tb3+ 4f−4f transitions were observed for both the samples. The luminescence properties at different doping concentrations were investigated. Concentration quenching at 8% was found, which is rather high, owing to the specially separated layered structure. The decay times of luminescence were also studied, which are consistent with the concentration quenching. In addition, energy diagram for the luminescence mechanism were also proposed. Considering the photoluminescence spectra and high concentration quenching, this compound is a potential mother compound for optical materials, especially for the green phosphors.
Biswajit Dalal, Xun Kang, Yoshitaka Matsushita, Alexei A. Belik, Yoshihiro Tsujimoto, and Kazunari Yamaura
American Physical Society (APS)
Yanchang Wang, Kentaro Yamamoto, Yoshihiro Tsujimoto, Toshiyuki Matsunaga, Datong Zhang, Zulai Cao, Koji Nakanishi, Tomoki Uchiyama, Toshiki Watanabe, Tsuyoshi Takami,et al.
American Chemical Society (ACS)
Hiroshi Yaguchi, Kotaro Fujii, Yoshinori Tsuchiya, Hiraku Ogino, Yoshihiro Tsujimoto, and Masatomo Yashima
American Chemical Society (ACS)
Hong Yan, Yoshitaka Matsushita, Kazunari Yamaura, and Yoshihiro Tsujimoto
Wiley
Chalcogenide-containing compounds have been widely studied as infrared nonlinear optical (NLO) materials. However, they have never been applied in the ultraviolet (UV) region owing to the high energy levels of chalcogen anions, leading to band gap narrowing. In this paper, we report the synthesis of a new UV NLO oxysulfide La 3 Ga 3 Ge 2 S 3 O 10 with an exceptionally wide band gap of 4.70 eV due to from the unique anion-ordered frameworks comprising 1D 1 ¥ [(Ga 3/5 Ge 2/5 ) 3 S 3 O 3 ] triangular tubes and 0D (Ga 3/5 Ge 2/5 ) 2 O 7 dimers of corner-sharing (Ga/Ge)S 2 O 2 and (Ga/Ge)O 4 tetrahedra, respectively. Second harmonic generation (SHG) measurements revealed that La 3 Ga 3 Ge 2 S 3 O 10 was phase matchable with twice the SHG response of KH 2 PO 4 . The results of theoretical calculations suggest that the strong SHG response is mainly attributable to the S-3 p and O-2 p orbitals in the occupied states. The anion-directed band-gap engineering may give insights into the application of NLO oxychalcogenides in the UV regions.
Hai L. Feng, Chang-Jong Kang, Pascal Manuel, Fabio Orlandi, Yu Su, Jie Chen, Yoshihiro Tsujimoto, Joke Hadermann, Gabriel Kotliar, Kazunari Yamaura,et al.
American Chemical Society (ACS)
Hong Yan, Yoshitaka Matsushita, Akira Chikamatsu, Tetsuya Hasegawa, Kazunari Yamaura, and Yoshihiro Tsujimoto
American Chemical Society (ACS)
A new ternary chromium disulfide, Ba9Cr4S19, has been grown out of BaCl2 molten salt. Single-crystal structure analysis revealed that it crystallizes in the centrosymmetric space group C2/c with lattice parameters: a = 12.795(3) Å, b = 11.3269(2) Å, c = 23.2057(6) Å, β = 104.041(3)°, and Z = 4. Ba9Cr4S19 comprises four face-sharing Cr-centered octahedra with disulfide ions occupying sites on each terminal face. The resulting Cr4S15 tetramer units are isolated by nonmagnetic Ba-centered polyhedra in the ab plane and barium disulfide (=Ba4(S2)2) layers along the c-axis. Following the structure analysis, the title compound should be expressed as [Ba2+]9[Cr3+]4[(S2)2–]4[S2–]11, which is also consistent with Cr2p X-ray photoemission spectra showing trivalent states of the Cr atoms. The unique Cr-based zero-dimensional structure with the formation of these disulfide ions can be achieved for the first time in ternary chromium sulfides, which adopt 1–3 dimensional frameworks of Cr-centered polyhedra.
Yuki Iwasa, Yu Su, Yoshinori Tsuchiya, Makoto Tatsuda, Kohji Kishio, Takayuki Yanagida, Fumi Takada, Taichiro Nishio, Yoshihiro Tsujimoto, Kotaro Fujii,et al.
Royal Society of Chemistry (RSC)
We report the synthesis, crystal structure, and optical properties of a new layered perovskite oxychloride, Ba3Y2O5Cl2.
Henrik Jacobsen, Hai L. Feng, Andrew J. Princep, Marein C. Rahn, Yanfeng Guo, Jie Chen, Yoshitaka Matsushita, Yoshihiro Tsujimoto, Masahiro Nagao, Dmitry Khalyavin,et al.
American Physical Society (APS)
We report on the structural, magnetic, and electronic properties of two new double-perovskites synthesized under high pressure; Pb2CaOsO6 and Pb2ZnOsO6. Upon cooling below 80 K, Pb2CaOsO6 simultaneously undergoes a metal--insulator transition and develops antiferromagnetic order. Pb2ZnOsO6, on the other hand, remains a paramagnetic metal down to 2 K. The key difference between the two compounds lies in their crystal structure. The Os atoms in Pb2ZnOsO6 are arranged on an approximately face-centred cubic lattice with strong antiferromagnetic nearest-neighbor exchange couplings. The geometrical frustration inherent to this lattice prevents magnetic order from forming down to the lowest temperatures. In contrast, the unit cell of Pb2CaOsO6 is heavily distorted up to at least 500 K, including antiferroelectric-like displacements of the Pb and O atoms despite metallic conductivity above 80 K. This distortion relieves the magnetic frustration, facilitating magnetic order which in turn drives the metal--insulator transition. Our results suggest that the phase transition in Pb2CaOsO6 is spin-driven, and could be a rare example of a Slater transition.
Jie Chen, Xiao Wang, Zhiwei Hu, Liu Hao Tjeng, Stefano Agrestini, Manuel Valvidares, Kai Chen, Lucie Nataf, Francois Baudelet, Masahiro Nagao,et al.
American Physical Society (APS)
Hong Yan, Akihide Kuwabara, Mark D. Smith, Kazunari Yamaura, Yoshihiro Tsujimoto, and Hans-Conrad zur Loye
American Chemical Society (ACS)
Single crystals of a new germanium oxysulfide La4(GeS2O2)3 were grown out of a BaCl2-CaCl2 eutectic flux, and the crystal structure was determined via single-crystal X-ray diffraction. Ivory-white ...