Browsing by Author "Tsuji, N"

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    Oxyhydrides of (Ca,Sr,Ba)TiO3 perovskite solid solutions
    (American Chemical Society, 2012-11-05) Sakaguchi, T; Kobayashi, Y; Yajima, T; Ohkura, M; Tassel, C; Takeiri, F; Mitsuoka, S; Ohkubo, H; Yamamoto, T; Kim, JE; Tsuji, N; Fujihara, A; Matsushita, Y; Hester, JR; Avdeev, M; Ohoyama, K; Kageyama, H
    The oxyhydride solid solutions (Ca,Sr)TiO3-xHx and (Sr,Ba)TiO3-xHx have been prepared by reducing the corresponding ATiO(3) oxides with calcium hydride. Under the reaction conditions examined, a hydride content of x = 0.1-0.3 was obtained for all compositions. Compared to our previous result with BaTiO3-xHx, the larger particle size in this study (20-30 mu m vs 170 nm) resulted in a somewhat lower hydride amount despite prolonged reaction times. We examined changes in cell volume, octahedral tilt angle, and site occupancy of different anion sites after conversion to oxyhydrides; it appears that these oxyhydrides fit the geometrical descriptions typical for regular ABO(3) perovskites quite well. The hydrogen release temperature, previously shown to be indicative of the hydride exchange temperature, however, does not scale linearly with the A-site composition, indicating a potential effect of chemical randomness. © 2012, American Chemical Society.
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    Synthesis and physical properties of the new oxybismuthides BaTi2Bi2O and (SrF)2Ti2Bi2O with a d1 square net
    (Physical Society of Japan, 2012-12-11) Yajima, T; Nakano, K; Takeiri, F; Hester, JR; Yamamoto, T; Kobayashi, Y; Tsuji, N; Kim, J; Fujiwara, A; Kageyama, H
    We have recently reported the d(1) square-lattice compound BaTi(2)Sb(2)O, which shows superconductivity at T(c) = 1.2K coexisting with a charge- or spin-density wave (CDW/SDW) state. Here, we successfully prepared two new oxybismuthides, BaTi(2)Bi(2)O and (SrF)(2)Ti(2)Bi(2)O, as the first Pn = Bi compounds in the ATi(2)Pn(2)O family. The CDW/SDW state disappeared for both compounds, presumably owing to the considerable interaction between the Ti-3d and Bi-6s orbitals. The complete suppression of the CDW/SDW instability resulted in an enhanced T(c) of 4.6 K for BaTi(2)Bi(2)O. However, (SrF)(2)Ti(2)Bi(2)O exhibits no superconductivity, suggesting the importance of the interlayer interaction for superconductivity. © 2012, Physical Society of Japan