Diffuse Ferroelectric Phase Transitions in Ba(Ti ₁ ‐ _y Zr _y )O ₃ Ceramics

Abstract

Very high and broad Curie maxima are observed in ceramic Ba(Ti1‐yZry)O3 mixed crystals, which are often used for the preparation of ceramic dielectrics. The ferroelectric‐to‐paraelectric phase transition of ceramic Ba(Ti1‐yZry)O3 was studied using dielectric measurements, quantitative DTA, X‐ray diffraction, and determination of the remanent polarization. At higher Zr concentrations, it was found that ferroelectric and paraelectric phases coexist in a wide temperature region. Up toy =0.16, the phase transition remains first order. The diffuse character is promoted by the small energy difference between the ferroelectric and paraelectric phases appearing at higher Zr content. It can be best described by a normal distribution of Curie temperatures using the phenome‐nological theory of Devonshire and the Newton‐Raphson mathematical approximation.