Theoretical analysis of fatigue in PZT ceramics on the basis of Landau theory

An experimental and theoretical analysis of the fatigue phenomena in PZT ce ramics with Pt electrodes is presented. The hysteresis loops measured at di fferent fatigue stages and at two temperatures have been analyzed theoretic ally on the basis of Landau theory-based lattice model. By estimating the m odel parameters, we obtained information about the possible mechanisms that contribute to fatigue. Evidence of the creation of ferroelectrically dead regions as well as the pinning of domain walls by defects has been found. T he contribution of both scenarios to the switching-induced degradation has been estimated at different fatigue stages. A comparison of the switching-i nduced degradation and temperature-induced one has been performed, showing additional evidence of the detected fatigue mechanisms. Good agreement betw een the theoretical P-r and E-c dependencies on the number-of-cycles and th e actual measured ones has been also found. This attests the suitability of Landau theory to study the switching and related phenomena.