Observation of a reentrant phase transition in incommensurate potassium
Observation of a reentrant phase transition in incommensurate potassium
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DOI：
10.1103/physrevb.88.054106
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发表时间：
2013-08-14
影响因子：
3.7
通讯作者：
McMahon, M. I.
中科院分区：
文献类型：
--
作者：
Lundegaard, L. F.;Stinton, G. W.;McMahon, M. I.
通过 X 射线粉末和单晶衍射的结合，确定了钾的主客体复合结构中的相变在 19 至 54 GPa 之间。不相称复合相K-III的客体组分在30.0(7) GPa下经历从C中心四方结构到A中心斜方结构的“相内”转变。在 39.7(5) GPa 下，客体组分经历重入转变回到以 C 为中心的四方形式。这是在元素复合结构中观察到的第一个此类重入转变。客体在 30.0(7) GPa 下的转变之前，结构的主体成分的 c 滑移对称性会丧失，并且直到在 39.7 GPa 下的折返转变后约 3 GPa 时才会恢复。
The phase transitions in the host-guest composite structure of potassium have been determined between 19 and 54 GPa by a combination of x-ray powder and single-crystal diffraction. The guest component of the incommensurate composite phase K-III undergoes an "intraphase" transition at 30.0(7) GPa from a C-centered tetragonal structure to an A-centered orthorhombic form. At 39.7(5) GPa, the guest component undergoes a reentrant transition back to the C-centered tetragonal form. This is the first such reentrant transition observed in the composite structures of the elements. The transition in the guest at 30.0(7) GPa is preceded by a loss of the c-glide symmetry of the host component of the structure, and this is not recovered until some 3 GPa after the reentrant transition at 39.7 GPa.