Effects of Sr substitution on the structural, dielectric, ferroelectric, and piezoelectric properties of Ba(Zr,Ti)O3 lead-free ceramics

We have systematically studied the effects of Sr substitution on the microstructure, crystal structure, Curie temperature, dielectric, ferroelectric, and piezoelectric properties of (Ba1-xSrx)(Zr0.05Ti0.95)O-3(0 <= x <= 0.40) ceramics prepared by the conventional solid-state reaction method. Both X-ray diffraction and dielectric measurements reveal that with increasing Sr content, the room-temperature crystal structure of the samples evolves from tetragonal to orthorhombic around x = 0.2 where the two phases coexist. Dielectric measurements show that Sr doping significantly reduces the Curie temperature (T-C) linearly from 114 degrees C for x = 0 to 10 degrees C for x = 0.4 with dT(C)/dx approximate to -265 degrees C/mol. Moreover, Sr doping causes linear shrinkage of the lattice constants and unit cell volume as well as considerable changes in the ferroelectric and piezoelectric properties. At room temperature, the sample with x = 0.11 exhibits enhanced piezoelectric properties with d(33) similar to 380 pC/N and the planar mode electromechanical coupling coefficient k(p) = 0.38. Our results provide useful reference for the optimization of Ba(Zr,Ti)O-3-based lead-free piezoelectric materials.