日本結晶学会誌
Online ISSN : 1884-5576
Print ISSN : 0369-4585
ISSN-L : 0369-4585
22 巻 , 6 号
選択された号の論文の3件中1~3を表示しています
  • 坂田 誠, 原田 仁平
    1980 年 22 巻 6 号 p. 387-405
    発行日: 1980/11/30
    公開日: 2010/09/30
    ジャーナル フリー
    The theoretical and experimental studies of anharmonic temperature factor in X-ray and neutron diffraction are reviewed since early works in 1963. These studies are in the framework of effective one body particle potential in which atoms are treated as independent oscillators.
    The experimental works are classified into two major groups : investigations of anti-centrosymmetric anharmonicity and centrosymmetric anharmonicity. It is pointed out that anti-centrosymmetric anharmonicity is well determined from the accurate Bragg intensity data at a certain temperature but centrosymmetric anharmonicity, because of the correlation of harmonic and anharmonic potential parameters, both of which are centrosymmetric. It is more reliable to determine the centrosymmetric anharmoni-city using the temperature dependence of integrated Bragg intensities unless extremely high Q data are collected.
    It is suggested that the degree of anharmonicity is much betterdescribed by a ratio of anharmonic term to harmonic term in one body particle potential than the magnitude of anharmonic potential parameter itself. The anharmonic effect is more significant for those substances which have smaller anharmonic potential coefficients.
    The relationships between anharmonicity of temperature factor and structural phase transition is discussed in the case of several perovskite substances.
  • 黒田 登志雄
    1980 年 22 巻 6 号 p. 406-417
    発行日: 1980/11/30
    公開日: 2010/09/30
    ジャーナル フリー
    A new interpretation on habits of ice growing from vapour is proposed. The primary habits of ice alternate three times (plates → -4°C→columns →-10°C plates →from -20°C to -35°C→columns) with decreasing temperature.
    The theory is based on a viewpoint that the surface of ice just below 0°C is covered with a quasi liquid layer, whose depth or coverage ϑ decreases with decrearing temperature, and then the growth mechanism of a surface changes also as followings : a) Vapour-Quasi Liquid-Solid-Mechanism (ϑ>1), b) Adhesive Growth on the surface with strong eigen adsorption by water molecules (0.01<ϑ< 1), and c) Two-Dimensional Nucleation Growth on the surface with little eigen adsorption (ϑ<0.01) . As the change in surface structure as well as growth mechanism depend on surface orientation, the complicated habits change is caused mainly by the combination of growth mechanism of each surface, i. e. basal {0001} -and prism {1010} -surface.
  • 青木 貞雄
    1980 年 22 巻 6 号 p. 418-421
    発行日: 1980/11/30
    公開日: 2010/09/30
    ジャーナル フリー
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