Direct evidence for Vogel-Fulcher freezing in relaxor ferroelectrics
Direct evidence for freezing in two relaxer ferroelectrics, PbMg1/3Nb2/3O3 and PbSc1/2Ta1/2O3, at a certain temperature T-f not equal 0K was obtained from the temperature dependence of the maximum relaxation time, tau(max), It was shown that tau(max)(T) follows the Vogel-Fulcher (VF) law, and tends toward infinity as temperature approaches T-f. The freezing temperature T-f derived from tau(max)(T) coincides with the value of T-f obtained from the fit of frequency, omega, dependence of the temperature, T-max, of the dielectric permittivity maximum to the same VF law. Thus, this result solves the controversy that the VF law for omega(T-max) may not correspond to the freezing of the spectrum. (C) 1998 American Institute of Physics.
Glazounov, AE Penn State Univ, Mat Res Lab, University Pk, PA 16802 USA Ecole Polytech Fed Lausanne, Lab Ceram, CH-1015 Lausanne, Switzerland
Cited References Count:16
Record created on 2006-08-21, modified on 2016-08-08