OPTICAL-ACTIVITY AND PHASE-TRANSITION OF PB1-XLAX(ZRYTIZ)(1-X 4)O-3/

Electric field dependences of optical activity and birefringence of Pb 0.92La0.08(Zr0.7Ti0.3)(0.98)O-3(PLZT(8/70/30)) were studied using the high-accuracy universal polarimeter (HAUP) method in a temperature reg ion between 0 degrees C and 90 degrees C. PLZT(8/70/30) was optically active in the low-temperature and inactive in the high-temperature pha ses. Furthermore it was revealed that gyration and birefringence in th e low-temperature phase manifested typical butterfly hysteresis loops with respect to electric fields. From analysis of Weissenberg photogra phs, the ceramics of both high- and low-temperature phases were found to consist of crystallites which were distributed in equal weight alon g the total solid angles. Using the combined evidence from HAUP and X- ray methods, it was clarified that the classes of the high- and low-te mperature phases are T-h and C-3, respectively.