抄録
Some experimental investigations have been made in order to understand the nature of phase transitions in the perovskite-type crystal CsPbCl3. Measurements of the birefringence and conoscopic observations confirm three phase transitions occurring at 37°C, 42°C and 47°C, respectively. The crystal system in each phase and the superstructure below 37°C are determined from the results of these measurements and an X-ray work. A dielectric measurement shows that CsPbCl3 is neither ferroelectric nor antiferroelectric in any of the phases. The transition entropies estimated from the result of a specific heat measurement are considerably smaller than that reported by Møller. The elastic compliance measured by the method of composite oscillator shows anomaly at each transition point. Temperature-dependent Raman spectra demonstrate the existence of “soft” modes which are overdamped near the transition temperatures. The nature of these phase transitions is discussed on the basis of the experimental results.
