Results of experimental investigation of relaxation aging processes in Pb(Zr,Ti)O 3 -based solid solutions after termination of external actions are presented. Heating, DC electric field, uniaxial pressure and some of their combinations were taken as external actions. In the main part of the present paper, we use heating as external action. The said processes are long-time one and are described by the logarithmic function of time.Reversible and nonreversible relaxation processes take place depending on the action intensity. The relaxation rate depends on the action intensity also, and the said dependence has nonlinear and nonmonotonic form if external action leads to domain disordering.The oxygen vacancies-based model for description of the long-time relaxation processes is suggested. The model takes into account oxygen vacancies on the sample's surface ends, their conversion into F þ -and F 0 -centers under external effects (due to the liberation of the pyroelectric charge) and subsequent relaxation of these centers into the simple oxygen vacancies after the actions termination. The initial sample's state is electroneutrality one. F-center formation leads to the violation of the original sample's electroneutrality, and generates DC electric field into the sample. Relaxation of F-centers is accompanied by decreasing of electric field, induced by them, and dielectric constant relaxation as consequent effect.

Formation of phases during the solid state synthesis of the [(Na 0.5 Bi 0.5 ) 0.80 Bа 0.20 ](Ti 1−у B у )O 3 system of solid solutions, with substitutions of zirconium and tin ions for titanium ones, has been investigated. It is demonstrated that the synthesis is a multi-step process which is accompanied by the formation of a number of intermediate phases (depending on the composition of the solid solution and the temperature of synthesis). Single phase solid solutions have been manufactured when the sintering temperature was increased to 1000 -1100 °C.An increase of the concentration of the substituting ions results in a linear increase in the size of the crystal cell. As a consequence the reduction of the tolerance factor and an increase of the stability of the antiferroelectric phase with respect to the ferroelectric one take place.

The article presents the results of research the pre-transitional features of the behavior of solid solutions based on lead zirconate-titanate. The presence of a “special” critical temperature [Formula: see text] on the temperature dependences of the permittivity [Formula: see text] and the remanent polarization [Formula: see text], preceding the temperature of the paraelectric phase transition at the Curie temperature [Formula: see text], is noted. In the temperature range [Formula: see text], the [Formula: see text] dependence obeys a power law. In the temperature range [Formula: see text], this law is not fulfilled. The results of X-ray experiments make it possible to associate this behavior with reversible disordering at [Formula: see text] of an ordered domain structure formed during the polarization of piezoelectric ceramics and with its irreversible disordering in the temperature range [Formula: see text]. This is due to the appearance of internal mechanical stresses in a polycrystalline ferroelectric due to irreversible depolarization of the samples at temperatures [Formula: see text].

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The paper presents results of studies of the formation of phases during the solid-state synthesis in the [(Na 0:5 Bi 0:5 Þ 0:80 Ba 0:20 ðTi 1Ày B y ÞO 3 system of solid solutions with B-site substitutions. The substitutions by zirconium, tin and ion complexes (In 0:5 Nb 0:5 Þ and (Fe 0:5 Nb 0:5 Þ have been studied. It has been found that the synthesis is a multi-step process associated with the formation of a number of intermediate phases (depending on the compositions and calcination temperatures). Single-phase solid solutions have been produced at the calcination temperatures in the interval 1000-1100 C. An increase in the substituting ions concentration leads to a linear increase of the crystal cell size. At the same time, the tolerance factor gets reduced boosting the stability of the antiferroelectric phase as compared to that of the ferroelectric phase.