Superparaelectric behaviours of relaxor ferroelectrics

A new approach to superparaelectrics is proposed. It is shown that it is possible to calculate the magnitude of dipole moments and concentration of polar regions on the basis of thermodynamic considerations for ferroelectric phase. The main conclusion is: the behaviours of thermodynamic parameters in the ferroelectric phase define dipole moments and their concentration in the superparaelectric phase. As in model relaxer - PMN, also in another relaxer materials, the magnitude of dipole moments of polar regions decreases with increasing temperature, while the dependency of polar region concentration on temperature is Gaussian-like. Results of experiments are presented also for ceramic materials Ba(Ti0.965Sn0.035)O-3, (Pb0.91La0.09)(Zr0.65Ti0.35)O-3, single crystal (Ba1.25Sr3.75)Nb10O30 and results of calculations on the basis of literature data are presented for 0.9PMN-0.1PbTiO(3) and (Pb0.88La0.12)(Zr0.4Ti0.6)O-3 (C) 1999 Published by Elsevier Science S.A. All rights reserved.