Grain Size Dependence of Piezoelectricity and Actuator Characteristics for Piezoelectric Ceramics

Abstract

The piezoelectric constant (d31) and the strain characteristics of the (Pb0.845Ba0.105Sr0.05) ((ZrxTi1-x) 0.95Sn0.045Nb0.005)O3 series (x=0.49, 0.52, 0.55), in which the grain size was controlled by hot-pressing (HP) conditions, were investigated. The piezoelectric constant (d31) was measured using an impedance analyzer. The strain characteristics was measured under two conditions. One is by applying DC electric field, and the other is by the durability under repetitious DC electric field. As a result, it is found that the piezoelectric constant, d31, and the actually found strain, δ, under DC electric field increase with increasing the grain size. The actually found strain, δ, under DC electric field larger than that obtained by calculated value, δcal, multiplying the d31 by DC electric field. Their difference, δ-δcal, increase with increasing the grain size. We considered that their difference, δ-δcal, was caused by the strain, δp, of domainial reorientation alone the intensity of electric field. The changing ratio of strain, which existed in durability under repetitious DC electric field application, increased with increasing the grain size. It is found that the decrease of δp led to this deterioration. The grain size dependence of the piezoelectricity and the strain characteristics was the largest with composition near the morphotropic phase boundary (MPB) of Zr=0.52.