Effects of octahedral tilting on the piezoelectric properties of Sr-doped lead zirconate titanate

(Pb1-xSrx)(Zr0.976-yTiyNb0.024)O-3 solid solutions were investigated to understand the relationship between structural changes caused by Sr substitution on the A-site and dielectric, and piezoelectric properties. As Sr was substituted for Pb, the Zr:Ti ratio was modified so that compositions had an optimised piezoelectric coefficient (d(33) ). d(33) was at a maximum in the tetragonal phase close to, but not at, the morphotropic phase boundary (MPB). As Sr content increased, optimised d(33) also increased from 410pC/N (x = 0) to 640pC/N (x = 0.12), commensurate with a decrease in the paraelectric to ferroelectric phase transition temperature (T-C ) from 350degreesC to 175degreesC. Low Sr concentrations (x = 0-0.08) contained 80nm ferrroelectric domains whereas high Sr concentrations (x = 0.12-0.16) contained fine-scale domains (20nm). In addition, [110] pseudocubic electron diffraction patterns revealed superlattice reflections at 1/2 {hkl} positions associated with rotations of the octahedra in anti-phase.