Thermal stability and expansion studies of cesium molybdates and cesium thorium molybdates

Abstract In Cs–Mo–O system, Cs 2 Mo n O 3 n +1 ( n = 1, 3, 5 and 7) were prepared by solid state route and n = 7 was established as the highest stable analog. Differential thermal analysis of the compound Cs 2 MoO 4 ( n = 1) in air showed a reversible phase transition followed by melting whereas compounds with n = 3, 5 and 7 did not show any phase transition up to their melting temperatures. Thermal expansion of all the molybdates were studied in vacuum using high temperature X-ray diffraction method. In quaternary Cs–Th–Mo–O system, Cs 2 Th(MoO 4 ) 3 and Cs 4 Th(MoO 4 ) 4 were synthesized by reacting cesium molybdate and thorium molybdate in 1:1 and 2:1 M ratios, respectively, at 873 K in air. Both compounds did not show any phase transition up to the melting and the compounds showed positive thermal expansion when heated in vacuum in the temperature range of 298–873 K.