Acoustic Emission During Phase Transition in Soft PZT Ceramics Under an Applied Electric Field

Abstract

In the present paper, it is proposed that a sudden appearance of a burst Acoustic Emission (AE) signal under an applied dc field, during temperature decrease cycle indicates the structural phase transition (PT) from cubic to tetragonal in soft PZT ceramics (PZT-5A, 5J & 5H). In general, the PT temperature determined by this method was found to increase with the increase in applied field. In addition to the AE signal observed at PT, a large number of AE signals—which are essentially different from the AE at PT—were also observed in the ferroelectric phase due to the presence of the field. These signals when subjected to pattern recognition resulted in two clusters indicating two different source mechanisms. It is suggested that "piezoelectric strain" and "strain due to domain alignment" are operative at lower (< 2 kV/cm) and higher (2–10 kV/cm) fields respectively. Communicated by Dr. George W. Taylor Keywords:: PZT ceramicsphase transitionacoustic emission ACKNOWLEDGMENTS This work was carried out under a DRDO sponsored project and the authors thank the concerned authorities. One of the authors, KPR is thankful to DRDO for the award of a SRF. The authors thank the authorities of Osmania University for providing the facilities. Notes Communicated by Dr. George W. Taylor