THERMOSONIMETRY AND THERMOMICROSCOPY OF THE PHASE-TRANSITION AND DECOMPOSITION OF CSCLO4

The phase transition and decomposition of CsClO4 was investigated by simultaneous TS-DTA measurement and high-temperature optical microscopy observation. The powdered CsClO4 samples yield a low-temperature TS peak (peaks a and b) at 110-230-degrees-C and a high-temperature TS peak (peaks c-e) at 560-630-degrees-C. The visual microscopic observation indicated that peak a arises from vigorous shaking of the particles in a pre-transition event. Peak b corresponds to the endothermic DTA peak due to the transition, during which movement of the bright lines indicative of a phase boundary was observed on thc surface of the particles. Peak c corresponds to the endothermic/exothermic peaks due to the melting/decomposition of CsClO4. Peaks d and e appear at thc corresponding endothermic peak temperatures of 615 and 628-degrees-C. It is suggested that peak c results both from the bubbling caused by oxygen generation and from thc precipitation of product CsCl. Peaks d and e are associated with the change in form of thc precipitates and their melting, respectively.