Polarization dynamics of polar nano-regions in Sr0.5Ba0.5Nb2O6 doped with combinations of Ce and Cr

Vugmeister's model (Phys Rev B 2006;73:174117) of relaxors has been extended and proven to be applicable to the polarization dynamics of PNRs in Sr0.5Ba0.5Nb2O6 (SBN50) doped with combinations of Ce and Cr. In this extended model, the distribution function in describing the real part of the complex permittivity can be scaled in terms of the activated dynamic scaling law rather than Vogel-Fulcher law for the uniaxial relaxor of SBN50. In the non-dispersion region below T-d (Burns temperature), mean-field theory is applicable. In the dispersion region, the activated dynamic scaling law has been shown to be valid in predicting the relationship between the frequency of the AC probing field and the maximum temperature. The dependence of the values of the critical exponent, theta nu (where nu is the exponent of the correlation length and theta is the "violation of hyperscaling" exponent) on the random fields induced by dopants is plausibly explained. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.