Publications by authors named "Takahito Terashima"

5 Publications

  • Page 1 of 1

Dehydration of Electrochemically Protonated Oxide: SrCoO with Square Spin Tubes.

J Am Chem Soc 2021 Oct 14;143(42):17517-17525. Epub 2021 Oct 14.

Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.

Controlling oxygen deficiencies is essential for the development of novel chemical and physical properties such as high- superconductivity and low-dimensional magnetic phenomena. Among reduction methods, topochemical reactions using metal hydrides (e.g., CaH) are known as the most powerful method to obtain highly reduced oxides including NdSrNiO superconductor, though there are some limitations such as competition with oxyhydrides. Here we demonstrate that electrochemical protonation combined with thermal dehydration can yield highly reduced oxides: SrCoO thin films are converted to SrCoO by dehydration of HSrCoO at 350 °C. SrCoO forms square (or four-legged) spin tubes composed of tetrahedra, in contrast to the conventional infinite-layer structure. Detailed analyses suggest the importance of the destabilization of the SrCoO precursor by electrochemical protonation that can greatly alter reaction energy landscape and its gradual dehydration (HSrCoO) for the SrCoO formation. Given the applicability of electrochemical protonation to a variety of transition metal oxides, this simple process widens possibilities to explore novel functional oxides.
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http://dx.doi.org/10.1021/jacs.1c07043DOI Listing
October 2021

Epitaxial Stabilization of SrCuO with Infinite CuO Layers.

Inorg Chem 2020 Jul 8;59(14):10042-10047. Epub 2020 Jul 8.

Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.

We report the epitaxial thin-film synthesis of SrCuO with infinitely stacked CuO layers composed of edge-sharing CuO square planes, using molecular-beam epitaxy. Experimental and theoretical characterizations showed that this material is a metastable phase that can exist by applying tensile biaxial strain from the (001)-SrTiO substrate. SrCuO shows an insulating electrical resistivity in accordance with the Cu valence state revealed by X-ray photoelectron spectroscopy. First-principles calculations also indicated that the unoccupied d band becomes substantially stabilized owing to the absence of apical anions, in contrast to ACuOCl (A = Sr, Ba) with an ACl block layer and therefore a -CuOCl octahedron. These results suggest that SrCuO is a suitable parent material for electron-doped superconductivity based on the CuO plane.
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http://dx.doi.org/10.1021/acs.inorgchem.0c01213DOI Listing
July 2020

Heavy interstitial hydrogen doping into SrTiO.

Chem Commun (Camb) 2018 Nov 1;54(88):12439-12442. Epub 2018 Oct 1.

Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.

We achieve the introduction of an extremly large amount of interstitial hydrogen into strontium titanate (SrTiO) by low-temperature hydrogen ion beam irradiation. The in situ transport measurements reveal an unprecedented thermal hysteresis of the resistivity.
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http://dx.doi.org/10.1039/c8cc07021kDOI Listing
November 2018

Epitaxial thin films of ATiO(3-x)H(x) (A = Ba, Sr, Ca) with metallic conductivity.

J Am Chem Soc 2012 May 18;134(21):8782-5. Epub 2012 May 18.

Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.

Epitaxial thin films of titanium perovskite oxyhydride ATiO(3-x)H(x) (A = Ba, Sr, Ca) were prepared by CaH(2) reduction of epitaxial ATiO(3) thin films deposited on a (LaAlO(3))(0.3)(SrAl(0.5)Ta(0.5)O(3))(0.7) substrate. Secondary ion mass spectroscopy detected a substantial amount and uniform distribution of hydride within the film. SrTiO(3)/LSAT thin film hydridized at 530 °C for 1 day had hydride concentration of 4.0 × 10(21) atoms/cm(3) (i.e., SrTiO(2.75)H(0.25)). The electric resistivity of all the ATiO(3-x)H(x) films exhibited metallic (positive) temperature dependence, as opposed to negative as in BaTiO(3-x)H(x) powder, revealing that ATiO(3-x)H(x) are intrinsically metallic, with high conductivity of 10(2)-10(4) S/cm. Treatment with D(2) gas results in hydride/deuteride exchange of the films; these films should be valuable in further studies on hydride diffusion kinetics. Combined with the materials' inherent high electronic conductivity, new mixed electron/hydride ion conductors may also be possible.
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http://dx.doi.org/10.1021/ja302465cDOI Listing
May 2012

Quasiparticle scattering induced by charge doping of iron-pnictide superconductors probed by collective vortex pinning.

Phys Rev Lett 2010 Dec 22;105(26):267002. Epub 2010 Dec 22.

Laboratoire des Solides Irradiés, CNRS UMR 7642 & CEA-DSM-IRAMIS, Ecole Polytechnique, Palaiseau, France.

Charge doping of iron-pnictide superconductors leads to collective pinning of flux vortices, whereas isovalent doping does not. Moreover, flux pinning in the charge-doped compounds is consistently described by the mean-free path fluctuations introduced by the dopant atoms, allowing for the extraction of the elastic quasiparticle scattering rate. The absence of scattering by dopant atoms in isovalently doped BaFe2(As(1-x)P(x))(2) is consistent with the observation of a linear temperature dependence of the low-temperature penetration depth in this material.
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http://dx.doi.org/10.1103/PhysRevLett.105.267002DOI Listing
December 2010
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