Measurements were made of phase transition temperatures and relaxation peaks in the internal friction of Pb0.975Ba0.01Ca0.01Sr0.005(Zr0.52Ti0.48)O3 plus 1.4wt%Bi2O3 and 0.3wt%GeO. The specimens were rectangular bars with dimensions of 30 x 10 x 0.9mm. Some specimens were subjected to polarization by low-temperature methods (423K, 30kV/cm, 0.5h) and others were γ-irradiated. Measurements were performed in a computer-controlled automatic resonant mechanical spectrometer, while heating at 1 to 5K/min, using frequencies of 930 or 1015Hz. Two maxima of internal friction were observed in Q-1 curves: PR at T1 = 382K (930Hz), T1 = 386K (1015Hz) and PF at T2 = 638K (930 and 1015Hz). The PF peak originated from the ferroelectric-paraelectric phase transformation, while PR could be explained in terms of Postnikov’s model which involved the interaction between mobile point defects and stationary 90° domain walls. The activation parameters of the PR peak, as deduced from the Arrhenius law, were 1.43 x 10-15s and 0.86eV.

The Influence of Point Defects on the Relaxation Processes in Ceramics of the PZT Type. B.Bruś, R.Zachariasz, J.Ilczuk, R.Zachariasz: Physica Status Solidi A, 2004, 201[4], 798-802