Phase Diagram and Dielectric Properties of (1–x)Ba(Ti1–yZry)O3 · xPbTiO3 Ceramics

Abstract

Ceramic (1–x)Ba(Ti1–yZry)O₃ · xPbTiO₃ (0 ≤ x, у ≤ 1) samples have been characterized by X-ray diffraction and dielectric measurements. The results have been used to map out the phase diagram of the system, which demonstrates the variation in the phase composition of the samples. It has been shown that, in the composition regions adjacent to the BaTiO₃–PbTiO₃ side and BaZrO₃ corner of the composition triangle, the samples consist of perovskite solid solutions that have tetragonal and cubic structures, respectively, at room temperature. In the intermediate composition region, the samples consist of different perovskite solid solutions similar in composition and structure. We have obtained composition dependences of the unit-cell symmetry and parameters for the solid solutions, their ferroelectric Curie temperature T_C, characteristic dielectric relaxation temperatures, dielectric permittivity ε, and dielectric loss tangent tanδ (at temperatures from 100 to 800 K and frequencies from 25 to 106 Hz) and analyzed the evolution of their dielectric properties with increasing BaZrO₃ content: from ferroelectric to properties of ferroelectric relaxors, reentrant relaxors, and dielectric relaxors of the dipole glass type.