Extinction corrections for a highly perfect crystal (SrTiO3)
Extinction corrections for a highly perfect crystal (SrTiO3)
复制标题
高度完美晶体 (SrTiO3) 的消光校正
DOI：
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发表时间：
1981
期刊：
影响因子：
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通讯作者：
H. Scheel
中科院分区：
文献类型：
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作者：
J. Hutton;R. Nelmes;H. Scheel
在从受消光影响非常大的数据中提炼可靠的热参数时，已经使用了来自SrTiO 3的高度完美晶体的精确中子衍射数据来评估Becker和Coppens的消光模型[Acta Cryst.（1974），A30，129-147，148-153; Acta Cryst.（1975），A31，417- 425]。该模型采用的近似方法在这种情况下并不明显合理，即（通常的）运动学近似和晶体微观结构的镶嵌块描述。然而，它表明，一个仔细选择的参数化内的整体mo-tel（例如高斯和洛伦兹函数之间的马赛克块方向的分布）可以产生一个均匀良好的描述消光本身-除了反射熄灭超过约90%的强度。改进的热参数是在非常好的协议与独立从lattice-dynamiccalculations获得的值。
Accurate neutron-diffraction data from a highly perfect crystal of SrTiO3 have been used to assess the extinction model of Becker & Coppens [Acta Cryst. (1974), A30, 129-147, 148-153; Acta Cryst. (1975), A31, 417--425] in refining reliable thermal parameters from data very strongly affected by extinction. The model incorporates approximations not evidently reasonable in this case - namely, the (usual) kinematical approximation and the mosaic-block description of crystal microstructure. However, it is shown that a careful choice of parameterization within the overall mo~tel (e.g. between a Gaussian and a Lorentzian function for the distribution of mosaicblock orientations) can yield a uniformly good description of the extinction per se - except for reflections extinguished by more than about 90% on intensity. The refined thermal parameters are in remarkably good agreement with values obtained independently from lattice-dynamicalcalculations.