Effects of grain size on the dielectric properties and tunabilities of sol-gel derived Ba(Zr0.2Ti0.8)O3 ceramics

Abstract

Barium zirconante titanate Ba(Zr0.2Ti0.8)O3 (BZT) ceramics were prepared using a sol–gel process. The effect of grain size and dc field on the dielectric properties of BZT ceramics were investigated. The coarse-grained sample undergoes a structural phase transition, but medium- and fine-grained samples showed diffuse phase transition characteristics. As the grain size decreased, the maximum dielectric constant and the transition temperature decreased. The fine-grained sample showed a ‘relaxor-like’ ferroelectric behavior, the dielectric relaxation rate follows the Vogel–Fulcher relation with and The dielectric constant is greatly suppressed and low loss is obtained under dc electric field. At room temperature (300 K) and 20 kV/cm, the tunability (k) and loss are 82% and 0.0034 for the coarse-grained sample.