Mechanical Loss and Elastic Modulus Associated with Phase Transitions in PLZT Ceramics

The phase transition in lanthanum modified lead zirconate-titanate ceramic of 6/60/40 is studied by mechanical loss Q-I and elastic modulus measurements. The shear elastic modulus measured from 50°C to 250°C shows that the Curie temperature is located at 180°C for the transition from cubic to rhombohedral phase. The Q-' curves at low frequencies show clearly a peak corresponding to such phase transition. This phase transition is c o n f m e d by measurements of Young's modulus and Q-I using resonance curve technique from -100°C to 300°C at kilohertz. Moreover, between 50°C and 90°C, the resonance curve recorded at kHz frequency shows two resonance peaks. Such existence of double peaks means that a phase transition takes place between two rhombohedral phases FE2 and FEl in the fenpelectric state. These phase transitions are also studied by DSC measurement.