GRAIN-SIZE DEPENDENCE OF PIEZOELECTRICITY AND ACTUATOR CHARACTERISTICS FOR PIEZOELECTRIC CERAMICS

The piezoelectric constant (d31) and the strain characteristics of the (Pb0.845Ba0.105Sr0.05) ((ZrxTi1-x)0.95Sn0.045 Nb0.005)O3 series (x=0. 49, 0.52, 0.55), in which the grain size was controlled by hot-pressin g (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 fiel d, and the other is by the durability under repetitious DC electric fi eld. As a result, it is found that the piezoelectric constant, d31, an d the actually found strain, delta, under DC electric field increase w ith increasing the grain size. The actually found strain, delta, under DC electric field larger than that obtained by calculated value, delt a(cal), multiplying the d31 by DC electric field. Their difference, de lta - delta(cal), increase with increasing the grain size. We consider ed that their difference, delta - delta(cal), was caused by the strain , delta(p), of domainial reorientation alone the intensity of electric field. The changing ratio of strain, which existed in durability unde r repetitious DC electric field application, increased with increasing the grain size. It is found that the decrease of delta(p) led to this deterioration. The grain size dependence of the piezoelectricity and the strain characteristics was the largest with composition near the m orphotropic phase boundary (MPB) of Zr=0.52.