Interpretation of Diffuse Streak Diffiraction Patterns from Single Crystals

スポンサーリンク

概要

• 論文の詳細を見る

• Recently, Honjo et al. found from the analyses of the streak patterns observed by themselves and some other authors for several crystals that the streak patterns for each crystal can be described as the cross sections of a set of "walls" pertaining to that crystal, passing through the reciprocal lattice points, cut by Ewald sphere. The walls for some crystals studied by them are listed in Table I. They mentioned also the temperature dependence of the intensity of the streaks, which suggested some role of the lattice vibrations in these phenomena. The theory of the thermal diffuse scattering tells us that the intensity of scattered rays from a crystal in a direction, corresponding to a point in reciprocal space with a vector distance q from the nearest reciprocal lattice point, is closely related to the inverse square of the frequency of the phonon with the wave vector q in that crystal. In this connection, we note that the transverse acoustic waves in each crystal, whose polarization vector lies in the direction of a linear or zigzag chain connecting nearest neighbor atoms in that crystal, are generally of low-frequency mode, because for these waves each atomic chain in that direction vibrates as a whole without any intrachain vibration and hence without much raising the potential energy of the crystal. This inference is supported by the recent investigations on the lattice vibrations of the individual crystals listed in Table I, except for barium titanate, which will be discussed separately below. Now, it can be seen from this Table that the. "walls" are the very planes in which all the wave vectors of the lowfrequency transverse acoustic waves lie. For monatomic crystals such as germanium and silicon crystals which contain two atoms per unit cell, the two polarization vectors associated with the two atoms, respectively, are equal and point to the <110>-direction for lattice waves under consideration. Then, a factor Σ_<k,k'>=_<1,2> exp {2πis・(γ_k-γ_k')}comes out in the intensity formula. If we use the usual expression, s=h_1b_1+h_2b_2+h_3b_3, this reduces to 4 cos^2{π(h_1+h_2+h_3)/2}, which was the form factor required for explaining the intensity modulation on the streak patterns observed for these crystals.

• 社団法人日本物理学会の論文
• 1964-07-05

著者

• Komatsu Kozo

  Department Of Physics Naniwa University

• Komatsu Kozo

  Department Of Physics University Of Osaka Prefecture

関連論文

• Theory of the Specific Heat of Graphite.
• Diffuse Streak Patterns from Various Crystals in X-Ray and Electron Diffraccion
• Interpretation of Diffuse Streak Diffiraction Patterns from Single Crystals
• Theory of the Specific Heat of Graphite II

スポンサーリンク