The Influence of Piezoelectric Grain Resonance on the Dielectric Spectra of LiNbO3 Ceramics

Abstract

It has often been suggested that the higher frequency dispersion (f∼107∼108 Hz) evident in the dielectric response of high‐permittivity ferroelectric ceramics might be associated with piezoelectrically driven resonant mechanical motion of individual grains. The hypothesis certainly appears reasonable, but so far no direct verification appears to have been attempted. Our discovery that the individual crystallite resonances are well preserved in poled LiNbO3 bicrystals suggested that we explore the dispersion of LiNbO3 ceramics. In both conventionally sintered and uniaxially hot‐pressed ceramics, the dielectric dispersion around 108 Hz has obvious resonant character. Using a modified ECAP computer program demonstrated that both the real and imaginary components of the impedance can be quantitatively described using the equivalent circuit models for the coupled individual grain resonances.