Dynamic structural disorder in cristobalite: neutron total scattering measurement and reverse Monte Carlo modelling
Dynamic structural disorder in cristobalite: neutron total scattering measurement and reverse Monte Carlo modelling
复制标题
方英石的动态结构无序：中子全散射测量和逆蒙特卡罗建模
DOI：
10.1088/0953-8984/13/3/304
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
D. Keen
中科院分区：
文献类型：
--
作者：
M. Tucker;M. Squires;M. Dove;D. Keen
使用中子总散射数据的约束逆蒙特卡罗模型研究了方英石高温 β 相和低温 α 相的原子结构。建模表明，β 相的无序涉及刚性 SiO4 四面体的旋转和位移，与“刚性单元模式”(RUM) 模型的预测一致。 α相的结构与β相显着不同，但仍具有一定程度的无序性。 β-方石英中氧原子的计算分布是连续的，而不是基于特定的晶体位点。没有证据表明 Si-O 距离与相应的 Si-O-Si 键角之间存在相关性，这与量子力学计算结果相反。三维漫散射是根据模型配置计算出来的，并且与实验电子衍射测量和 RUM 模型的预测一致。 β 相的结构或漫散射对温度的依赖性很小。
The atomic structure of cristobalite in both its high-temperature β-phase and low-temperature α-phase has been studied using constrained reverse Monte Carlo modelling of neutron total scattering data. The modelling has shown that the disorder of the β-phase involves rotations and displacements of rigid SiO4 tetrahedra, consistent with the predictions of the `rigid-unit mode' (RUM) model. The structure of the α-phase is significantly different from that of the β-phase, but still has a degree of disorder. The calculated distribution of oxygen atoms in β-cristobalite is continuous rather than based on specific crystallographic sites. There is no evidence for correlations between the Si-O distance and the corresponding Si-O-Si bond angles, contrary to quantum mechanical calculation findings. The three-dimensional diffuse scattering has been calculated from the model configurations, and is found to be in agreement with experimental electron diffraction measurements and the predictions of the RUM model. There is little significant temperature dependence of the structure or diffuse scattering in the β-phase.