Syntheses, structures, anomalous phase transition and optical properties of two new polymorphic alpha- and beta-LiMoPO6
Syntheses, structures, anomalous phase transition and optical properties of two new polymorphic alpha- and beta-LiMoPO6
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两种新型多晶型α-和β-LiMoPO6的合成、结构、反常相变和光学性质
DOI：
10.1039/c9dt03451j
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发表时间：
2019
影响因子：
4
通讯作者：
Wu Yicheng
中科院分区：
文献类型：
--
作者：
Liu Haonan;Wu Hongping;Yu Hongwei;Hu Zhanggui;Wu Yicheng
利用高温固溶技术成功合成了α-和β-LiMoPO6两种新的多晶相，并通过单晶x射线衍射对其结构进行了表征。α-LiMoPO6在正交空间群Pbcn （No. 60）中结晶，a = 12.1141(4) Å， b = 8.9251(3) Å， c = 8.7389(3) Å； β- limopo6在单斜空间群P21/c （No. 14）中结晶，a = 6.3441(3) Å， b = 7.5949(3) Å， c = 9.3430(4) Å， β = 94.546(4)°。这两种结构都表现出相似的由MoO6八面体和PO4四面体组成的三维框架。有趣的是，观察到一个反常的相变，即高温β-LiMoPO6相的密度大于低温α-LiMoPO6相。详细的结构分析表明，异常相变主要源于其结构中之字形[MoO3O3PO]∞链的“拉直”效应。此外，还报道了两种化合物的光学和热学性质。
New polymorphous phases, α- and β-LiMoPO6, have been successfully synthesized by the high temperature solution technique and their structures have been determined by single crystal X-ray diffraction. α-LiMoPO6 crystallizes in the orthorhombic space group Pbcn (No. 60) with a = 12.1141(4) Å, b = 8.9251(3) Å and c = 8.7389(3) Å, while β-LiMoPO6 crystallizes in the monoclinic space group P21/c (No. 14) with a = 6.3441(3) Å, b = 7.5949(3) Å, c = 9.3430(4) Å and β = 94.546(4)°. Both structures exhibit a similar three-dimensional (3D) framework composed of MoO6 octahedra and PO4 tetrahedra. Interestingly, an anomalous phase transition, i.e. the high-temperature β-LiMoPO6 phase exhibiting larger density than the low-temperature α-LiMoPO6, has been observed. Detailed structural analyses show that the anomalous phase transition mainly originates from the ‘straightened’ effect of the zigzag [MoO3O3PO]∞ chains in their structures. Furthermore, the optical and thermal properties of two compounds are also reported.