Enhanced dielectric and piezoelectric properties of xBaZrO3-(1-x)BaTiO3 ceramics

摘要

xBaZrO3-(1-x)BaTiO3 solid solutions (x = 0, 0.04, 0.06, 0.08, 0.12, and 0.18) synthesized via conventional solid state reaction method exhibit piezoelectric coefficients comparable to those of “hard” PZT-8, PZT-4, and even “soft” PZT-5 A. Doping also improves the poling efficiency of xBaZrO3-(1-x)BaTiO3 ceramics. Study of temperature dependence of the dielectric and piezoelectric properties reveal the following. Doping lowered the Curie point but raised the temperatures of the other two transformations. The diffused phase transition behavior has been enhanced with increasing content of BaZrO3, but x ≤ 0.18 is not enough to show a relaxor behavior. Piezoelectric responses show peaks at transformation temperatures and exhibit the best stability in the orthorhombic phase. Significant improvement in room temperature piezoelectric and electromechanical responses (d33 = 420pC/N, d31 = -138pC/N, and kp = 49%) comparable to PZT-5 A is achieved at a composition of x = 0.06 (1400 °C 100 h sintered), which brings the rhombohedral-orthorhombic transition to the ambient temperature. Enhanced piezoelectric properties are mainly attributed to a series of microscopic phase transformations due to the presence of internal structural gradient. Other possible contributions such as domain structures and constrained negative stiffness effect have also been discussed.