STUDIES ON THERMAL-DECOMPOSITION OF CESIUM SODIUM FLUOROTHIOCYANATOBISMUTHATES(III) AND IODOTHIOCYANATOBISMUTHATES(III)

The thermal decomposition of caesium-sodium fluoro- and iodothiocyanatobismuthates(III) having the formulae Cs2Na[Bi(SCN)3I3], Cs2Na[Bi(SCN)2I4], Cs2Na[Bi2-(SCN)5I4], Cs2Na[Bi2(SCN)7F2] and Cs2Na[Bi2(SCN)6F3] has been examined. The thermal analysis curves of the complexes and the results of chemical and X-ray analyses of the solid pyrolysis products are presented. The results have been used to determine the three stages of thermal decomposition. Reactions occurring in each stage are described. The reaction order and activation energy of each stage have been calculated by means of the methods of Coats-Redfern and Zsako. The mechanisms of decomposition and the thermal stability of all caesium-sodium halidothiocyanatobismuthates(III) so far obtained have been compared.