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

Abstract
The phase transition in lanthanum modified lead zirconate-titanate ceramic of 6/60/40 is studied by mechanical loss Q^-1 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^-1 curves at low frequencies show clearly a peak corresponding to such phase transition. This phase transition is confirmed by measurements of Young's modulus and Q^-1 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 FE1 in the ferroelectric state. These phase transitions are also studied by DSC measurement.