日本結晶学会誌
Online ISSN : 1884-5576
Print ISSN : 0369-4585
ISSN-L : 0369-4585
56 巻 , 1 号
選択された号の論文の16件中1~16を表示しています
特集
1.新時代の結晶学-X線自由電子レーザー
最近の研究から
  • 大串 研也, 大隅 寛幸, 山浦 淳一, 有馬 孝尚
    2014 年 56 巻 1 号 p. 36-42
    発行日: 2014/02/28
    公開日: 2014/03/05
    ジャーナル フリー
    We have performed resonant X-ray diffraction experiments at the Ir L absorption edges for a post-perovskite compound CaIrO3 with a Ir4+:(t2g5 electronic configuration. By observing the magnetic signals, we could clearly see that the magnetic structure was a striped ordering with antiferromagnetic moments along the c axis and that the wave function of a t2g hole is strongly spin-orbit entangled, the Jeff=1/2 state. The observed spin arrangement is consistent with a theoretical work predicting a unique superexchange interaction called the quantum compass model. Our studies stimulate further studies for developing novel quantum states in iridium oxides.
  • 福田 功一郎
    2014 年 56 巻 1 号 p. 43-48
    発行日: 2014/02/28
    公開日: 2014/03/05
    ジャーナル フリー
    We have successfully prepared the three types of highly c-axis-oriented polycrystalline materials of lanthanum silicate apatite(La9.33Si6O26, La9.50Si6O26.25 and La9.50Si5.87O26)by isothermal heating of the diffusion couples consisting of La2SiO5 and La2Si2O7 at 1873 K for 50-100 h. The resulting polycrystals were subsequently characterized using polarizing microscopy, X-ray diffration and impedance spectroscopy. The annealed couples were mechanically processed, and the thin-plate electrolytes consisting of the grain-aligned polycrystals were obtained. The oxide-ion conductivity along the c-axis of oxygen hyper-stoichiometric apatite, La9.50Si6O26.25,was ca. 2.5 times higher than that of oxygen stoichiometric apatite, La9.33Si6O26, at 723-973 K. The polycrystalline material of Si-deficient apatite, La9.50Si5.87O26, showed, among the three types of apatite polycrystals, the highest conductivity above 850 K; the conductivity at 873 K was 4.2×10−2 S/cm.
  • 杉本 邦久, 藤原 明比古, 上町 裕史, 前川 雅彦
    2014 年 56 巻 1 号 p. 49-53
    発行日: 2014/02/28
    公開日: 2014/03/05
    ジャーナル フリー
    A new air-stable cyclohexasulfur(cyclo-S6)was discovered in the crystal of 3,5-diphenyl-1,2,4-dithiazol-1-ium(dpdti)iodide, formed by cocrystallization. The dpdti was synthesized via an oxidation reaction of thiobenzamide with iodine in benzene. Two kinds of crystal habits—brock-shaped(crystal-A)and needle-shaped(crystal-B)—were obtained following recrystallization from acetonitrile solvent. All molecules in crystal-A and -B were identified through single-crystal X-ray structure analysis using a synchrotron X-ray. The cyclic-S6 molecule in the crystal-A is a self-assembly enclosed by the dpdti cation and iodide anion, and is assumed to contribute to their stability in the crystal, akin to the Sn ring in zeolites and sodalites. In the context of cyclo-S6, cocrystallization is constituted by weak intermolecular effects such as the van der Waals force. Crystal engineering of cocrystals resulted in air-stable cyclo-S6. This study presents a method to turn an unstable molecule into a stable crystalline molecule that maintains its origin structure, with an aim of predicting its stability in future studies.
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