日本結晶学会誌
Online ISSN : 1884-5576
Print ISSN : 0369-4585
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最近の研究動向
連載企画 SHELXL入門講座
ミニ特集 中性子回折で拓く鉱物結晶学
  • 小松 一生, 山根 崚, 則竹 史哉, 町田 真一
    59 巻 (2017) 6 号 p. 293-300
    公開日: 2017/12/31
    ジャーナル フリー

    Here I discuss a problem of an inconsistency among various experiments and calculations for ice XV, the ordered form of ice VI, i.e., neutron diffraction observations suggest antiferroelectrically ordered structures, which disagree with dielectric measurement and theoretical studies, implying ferroelectrically ordered structures. Our recent neutron diffraction experiments and DFT calculations support a scenario in which several kinds of ordered configuration coexist, which was proposed more than 40 years ago by Kamb. More recently published arguments in terms of this issue are also briefly reviewed.

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  • 服部 高典, 佐野 亜沙美, 町田 真一, 阿部 淳, 舟越 賢一, 岡崎 伸生
    59 巻 (2017) 6 号 p. 301-308
    公開日: 2017/12/31
    ジャーナル フリー

    PLANET is a powder neutron diffractometer dedicated to high-pressure experiments. By combining the intense neutron source of J-PARC and the high-pressure devices designed for time-of-flight powder neutron diffraction, precise structure analysis of crystal, liquid, and amorphous solids is possible over wide pressure and temperature range of 0~20 GPa and 77~2,000 K. This beamline is effective for various studies in geophysics, planetary science, physics and chemistry. This paper overviews the beamline and introduces recent results obtained at PLANET.

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  • 奥地 拓生, プレジャブ ナランゴー, 富岡 尚敬
    59 巻 (2017) 6 号 p. 309-315
    公開日: 2017/12/31
    ジャーナル フリー

    Water in the Earth has been transported from the oceans into its deep interior, where it forms hydrous deep mantle minerals. Wadsleyite [(Mg,Fe)2SiO4] has been considered as one of the most important host minerals incorporating this type of water as hydroxyl groups. To constrain the capacity of water in its structure and also to understand the effect of such water on its physical properties, it is essential to quantitatively determine the hydrogenʼs site and occupancy in the wadsleyite structure. Here we conduct a neutron time-of-flight single-crystal Laue diffraction study of it. Single crystals, which have size and quality suitable for this method, were successfully synthesized by a slow-cooling method at the relevant high pressure and temperature condition. The results unambiguously demonstrate a unique incorporation mechanism of hydrogen into the wadsleyite structure.

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