Structural analysis of molten Cs2So4
Abstract
The structure of molten Cs2SO4 has been investigated using the radial distribution function based on X-ray scattered intensity data collected at ca. 1100 °C and has been analysed by the correlation method. The SO4 tetrahedron which exists in the crystalline state of Cs2SO4 has been shown to be preserved in the molten state. The most likely model for the short-range arrangement is that ca. 7/8 of the Cs atoms occupy the corner-sharing sites with an average Cs—O distance of 3.07 Å and the others occupy the face-sharing sites with an average Cs—O distance of 3.48 Å. The most likely model for the long-range arrangement within 10 Å is simulated by CaF2-type packing where the Ca and F atoms are replaced by the SO4 tetrahedron and the Cs atom, respectively. One Cs2SO4 unit is surrounded by ca. 18 Cs2SO4 units with an average inter-unit distance of 7.56 Å. The structure of molten Cs2SO4 has been discussed in relation to those of molten M2SO4(M = Li, Na, K and Ag).