Superspace approach to high pressure superstructures
Superspace approach to high pressure superstructures
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DOI：
10.1080/08957959.2013.822076
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发表时间：
2013-08-20
影响因子：
2
通讯作者：
van Smaalen, Sander
中科院分区：
文献类型：
--
作者：
Bykov, Maxim;Bykova, Elena;van Smaalen, Sander
金刚石压砧单元中的单晶X射线衍射已被证明是研究极端条件下物质的有力工具。高对称性低压结构和低对称性高压超结构之间的位移区界相变是压力诱导过程的重要组成部分。然而，这种超结构的分析通常是复杂的低角分辨率和有限的倒易空间覆盖。这导致在结构求解和细化期间不利的数据/参数比。超空间方法是描述连续调制结构的一种成熟方法，但它并不经常应用于高压相变。在这里，我们讨论了超空间方法的描述和晶体化学分析的高压超结构的优势。这种方法的主要思想说明的例子同构FeOCl和CrOCl，形成不同的超结构以上15 GPa。
Single-crystal X-ray diffraction in a diamond anvil cell has proven to be a powerful tool for studying matter at extreme conditions. Displacive zone-boundary phase transitions between a high-symmetry low pressure structure and a low-symmetry high pressure superstructure represent a significant part of pressure-induced processes. However, the analysis of such superstructures is usually complicated by low angular resolution and limited reciprocal space coverage. This leads to unfavorable data/parameter ratio during the structure solution and refinement. The superspace approach is an established method to describe commensurately modulated structures, however it is not often applied to high pressure phase transitions. Here, we discuss the advantages of the superspace approach for the description and crystal-chemical analysis of high pressure superstructures. The main ideas of this approach are illustrated by the examples of isostructural FeOCl and CrOCl, forming different superstructures above 15 GPa.