Dielectric nonlinearity in a compositionally graded lead zirconate titanate structure

The dielectric response of a compositionally graded lead zirconate titanate (PZT) structure was studied as a function of frequency and amplitude of measuring field. The nonlinear behavior was observed above "threshold" value E-t of electric field strength giving rise to field-dependent dielectric properties. Just above E-t the nonlinearity was well fitted by the empirical Rayleigh relations. The values of Rayleigh coefficients were observed to be different from those of homogenous PZT films. The analysis of the nonlinearity allows us to suggest higher density of domain walls and/or their better mobility in graded structure.