The Problem of Phase Transitions in PZT Based Solid Solutions, Pb(Mg 1/3 Nb 2/3 )O 3 , Pb(In 1/2 Nb 1/2 )O 3 and "Relaxor Ferroelectricity." 1. Experimental Results and Phase Diagrams for PZT Based Solid Solutions.

In the present paper the phenomena predicted in [1] for substances with coexisting FE and AFE phases coexistence is experimentally shown. The examples of PZT-based solid solutions are investigated. The solid solutions for which FE and AFE states have equal or close energy stability possess the following experimental properties: - a high degree of (paraelectric) PE phase transition diffuseness; - an essential dispersion of permittivity in the region of diffuse maximum of the dependences ℇ′(T) and ℇ′′(T) and fulfilment of the Fogel-Fülcher law; - an increase of the measuring AC field amplitude E 0 leads to a linear decrease of T′ m and to an increase of ℇ′(T′ m ); the tangent of T′ m (E 0 ) dependence decreases with an increase of AC field frequency; - the presence of effects which point to the existence of polar phase domains at temperatures essentially higher than T′ m and T′′ m ; - dependence of their properties on the sample's history; - a long-duration relaxation. [ABSTRACT FROM AUTHOR]