Grain-size effects on properties of some ferroelectric ceramics

TLDR

Ferroelectric properties arise from intrinsic single‑domain effects and domain wall motion. The study prepared hot‑pressed lead‑titanate‑zirconate ceramics of varying grain size, measured their dielectric and piezoelectric properties, and modeled each grain as a monodomain with a Gaussian‑distributed transition temperature to reproduce the temperature dependence of the dielectric constant. The model qualitatively explains the observed similarities between lead‑titanate‑zirconate and barium‑titanate ceramics, linking them to diffuse phase transitions.

Abstract

Hot-pressed ceramics of the lead titanate zirconate system with different grain sizes were prepared and some of their electrical properties measured. The values of the dielectric and piezoelectric properties were analysed together with information on barium titanate ceramics already published in the literature. Many similarities were found between both systems. There are two main contributions to the properties; the single-crystal single-domain intrinsic effect and the contribution of the wall motion. The intrinsic effect is analysed considering the grains as monodomains. A model is developed which proposes that each grain has a different transition temperature Tc. The Tc values are taken as following a Gaussian distribution and the behaviour of the dielectric constant against temperature is computed and checked with experimental results. All the results can be explained qualitatively with the model; a connection between findings and the idea of diffuse phase transitions is outlined.