X-Ray Study of Orientational Disorder in Crystals
X-Ray Study of Orientational Disorder in Crystals
复制标题
晶体取向无序的 X 射线研究
DOI：
10.5940/jcrsj.24.122
复制
发表时间：
1982
期刊：
影响因子：
--
通讯作者：
Y. Shinnaka
中科院分区：
文献类型：
--
作者：
Y. Shinnaka
由多原子基团组成的分子晶体和离子晶体表现出伴随着多原子基团的取向无序的“取向转变”。总结了作者及其合作者近十年来关于取向无序X射线研究的一些课题。基于“12取向”模型对NH4NO3和RbNO3的CsCI型立方相中NO3离子取向无序所观测到的X射线漫散射进行了分析。讨论了Matsubara（Zernike理论）、Naya（随机相近似）和Nagai（Bethe方法）给出的多取向体系X射线漫散射的强度公式。在RbNO3和NaCN的NaCI型立方相中观察到了C44模式引起的X射线温度漫散射异常。通过考虑方向和声声子之间的线性耦合，可以解释观察到的漫散射的温度依赖性。
Molecular crystals and ionic crystals which consist of polyatomic groups exhibit “orientational transitions” accompanied by an orientational disorder of polyatomic groups. Some topics on X-ray studies of the orientational disorder, which have been studied by the present author and his collaborators in a recent decade, are summarized.The observed X-ray diffuse scatterings due to the orientational disorder of NO3-ions in the CsCI-type cubic phases of NH4NO3 and RbNO3 are analysed on the basis of “12-orientation” model. The intensity formulae of X-ray diffuse scattering for polyorientation system, which have been given by Matsubara (Zernike's theory), by Naya (random phase approximation) and recently by Nagai (Bethe's method), are discussed.Anomalies of X-ray temperature diffuse scatterings due to C44 mode are observed in the NaCI-type cubic phases of RbNO3 and NaCN. By taking account of a linear coupling between the orientations and acoustic phonons, the observed temperature dependences of the diffuse scatterings are explained.