Large piezoelectric anisotropy and high hydrostatic piezoelectric activity due to an appreciable orientation effect and porosity in novel 2–2–0 composites

Abstract

The polarization orientation effect and porosity effect on the piezoelectric properties and related parameters are studied in 2–2-type composites based on domain-engineered relaxor-ferroelectric [011]-poled single crystals. The parameters, which are of great interest, are an anisotropy of the piezoelectric coefficients [Formula: see text], an anisotropy of the energy-harvesting figures of merit [Formula: see text] and the hydrostatic piezoelectric coefficient [Formula: see text]. An orientation of the main crystallographic axes in each polydomain single-crystal layer is described by angles [Formula: see text] and [Formula: see text]. Diagrams built for the first time show the ([Formula: see text]) regions, where a large anisotropy of [Formula: see text] (or [Formula: see text]) is achieved, and where inequality [Formula: see text] 1000 pC/N holds. A large local max [Formula: see text] = 1930 pC/N is achieved in a 2–2–0 PZN–0.065PT-based composite at the longitudinal piezoelectric coefficient [Formula: see text] = 2290 pC/N and figure of merit [Formula: see text] = 1.02[Formula: see text]10[Formula: see text] Pa[Formula: see text]. The aforementioned large parameters are to be of value in piezoelectric sensing, energy harvesting and hydroacoustics.