High pressure studies of A(2)Mo(3)O(12) negative thermal expansion materials (A(2)=Al-2, Fe-2, FeAl, AlGa)

作者：Young Lindsay; Gadient Jennifer; Gao Xiaodong; Lind Cora^*

来源：Journal of Solid State Chemistry, 2016, 237: 121-128.

DOI：10.1016/j.jssc.2016.02.004

• Negative thermal expansion
• High pressure
• Synchrotron radiation
• in-situ studies
• Phase transitions
• Scandium tungstate family

High pressure powder X-ray diffraction studies of several A(2)Mo(3)O(12) materials (A(2)=Al-2, Fe-2, FeAl, and AlGa) were conducted up to 6-7 GPa. All materials adopted a monoclinic structure under ambient conditions, and displayed similar phase transition behavior upon compression. The initial isotropic compressibility first became anisotropic, followed by a small but distinct drop in cell volume. These patterns could be described by a distorted variant of the ambient pressure polymorph. At higher pressures, a distinct high pressure phase formed. Indexing results confirmed that all materials adopted the same high pressure phase. All changes were reversible on decompression, although some hysteresis was observed. The similarity of the high pressure cells to previously reported Ga2Mo3O12 suggested that this material undergoes the same sequence of transitions as all materials investigated in this paper. It was found that the transition pressures for all phase changes increased with decreasing radius of the A-site cations.

• 出版日期2016-5