High-pressure synthesis and crystal structure of the strontium tungstate Sr3W2O9
High-pressure synthesis and crystal structure of the strontium tungstate Sr3W2O9
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钨酸锶Sr3W2O9的高压合成及晶体结构
DOI：
10.1107/s2053229617017879
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
H.Sakurai
中科院分区：
文献类型：
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作者：
D. Urushihara;T. Asaka;K. Fukuda;H.Sakurai
采用高压合成技术合成了钨酸锶化合物Sr3W2O9。用单晶X射线衍射法和透射电子显微镜对晶体结构进行了表征。该结构是Ba3W2O9高压相的杂多型结构，具有三角对称性的角共八面体。Sr3W2O9具有C2/c对称性的单斜晶胞。这种结构的一个特征是打破了Ba3W2O9高压相中存在的三重旋转对称性。[Al_2O_3]层(A=Ba，Sr)的层间距显著缩短，晶体结构发生扭曲。在Sr3W2O9中，W6+离子在WO6八面体中发生偏心位移。在Ba3W2O9的高压相中也观察到这样的位移。
The strontium tungstate compound Sr3W2O9 was prepared by a high-pressure synthesis technique. The crystal structure was determined by single-crystal X-ray diffraction and transmission electron microscopy. The structure was found to be a hettotype structure of the high-pressure phase of Ba3W2O9, which has corner-sharing octahedra with a trigonal symmetry. Sr3W2O9 has a monoclinic unit cell of C2/c symmetry. One characteristic of the structure is the breaking of the threefold rotation symmetry existing in the high-pressure phase of Ba3W2O9. The substitution of Sr at the Ba site results in a significant shortening of the interlayer distances of the [AO3] layers (A = Ba, Sr) and causes a distortion in the crystal structure. In Sr3W2O9, there is an off-centre displacement of W6+ ions in the WO6 octahedra. Such a displacement is also observed in the high-pressure phase of Ba3W2O9.