LINEARIZATION OF DIELECTRIC NONLINEARITY BY INTERNAL BIAS FIELDS

The dielectric response of BaTiO3 and PZT ceramics to an applied ac field is found to be nonlinear even at weak signals. The nonlinearity shows a substantial dependence on acceptor doping and a pronounced aging behaviour. The nonlinear dielectric behaviour epsilon(E) can be described by a polynomial fit using only even powers up to the fourth. The polynomial coefficients decrease with time. The aging of the dielectric nonlinearity is correlated to the buildup of the internal bias.