Microstructure and piezoelectric properties of Ba(Ti_0.8Zr_0.2)O₃- (Ba_0.7Ca_0.3) TiO₃ lead-free ceramics

Lead-free piezoelectric Ba(Ti_0.8Zr_0.2)O₃- (Ba_0.7Ca_0.3)TiO₃ (BZT-xBCT) ceramics with high piezoelectric coefficient were synthesized by the conventional solid state reaction method. The effect of the contents of BCT on the system microstructure, piezoelectric and dielectric property has been investigated. The results showed that the main phase of BZT-xBCT ceramics was perovskite phase when x was 0.45 to 0.60, and a small amount of second phase (CaTiO₃) was detected when x>0.50.BZT-xBCT ceramics with x=0.50 had an optimized piezoelectric characterization, its dielectric constant, piezoelectric constant d₃₃, electromechanical coupling factor k_p, mechanical quality factor Q_m and the frequency coefficient N_p were 2 900, 385 pC/N, 0.456, 124 and 2 740 Hz·m respectively. Theese results indicate that the BZT-xBCT with the compositions near the morphotropic phase boundary (MPB) is a hopeful candidate material to replace the lead-based piezoelectric materials.