Nonlinear contributions to the quasistatic and the first-harmonic dielectric response in relaxor systems
Jožef Stefan Institute - P.O. Box 3000, 1001 Ljubljana,
Accepted: 18 December 2000
Nonlinear dielectric response in relaxor systems was studied as a function of the ac and dc electric field. Significant frequency dependence was found in the nonlinearity a3. The crossover temperature dependence of a3 -a fingerprint of the spherical glass freezing-was confirmed to exist even in the static limit. Beside the expected reflection of the third harmonic component additional nonlinear contribution was found in the nonlinear dependence of the first harmonic response . It is shown that this second contribution to the field dependence of and also the quasistatic measurements of the nonlinear dielectric response throughout the glassy-to-ferroelectric crossover region can be described by the spherical random-bond-random-field model of relaxor ferroelectrics.
PACS: 78.20.Ci – Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity) / 64.70.Pf – Glass transitions / 77.84.Dy – Niobates, titanates, tantalates, PZT ceramics, etc
© EDP Sciences, 2001