Antiferroelectric and ferroelectric phase transitions of the displacive and order-disorder type in PbZrO3 and PbZr1-xTi x O3 single crystals

Abstract

For PbZrO3 and PbZr0.99Ti0.01O3 single crystals the first order Raman light scattering spectra in the paraelectric phase have been analysed. In lead zirconate two kinds of crystals, with and without a transient phase, were investigated. It was found that temperature dependence of the defect-induced soft mode frequency in the paraelectric phase has a negligible contribution to the low-frequency dielectric response. From the point of view of strong dielectric relaxation in the range of 106–109 Hz, which originates in a disorder of the lead sites, crossover of the order-disorder and displacive type of antiferroelectric phase transition in lead zirconate is considered: the phase transition mechanism is neither purely displacive nor order-disorder. Contribution of physical phenomena responsible for the ε(ω,T) dielectric response at low frequencies of an external electric field are described.