The effects of CuO-doping on dielectric and piezoelectric properties of Bi0.5Na0.5TiO3–Ba(Zr,Ti)O3 lead-free ceramics

CuO-doped lead-free ceramics based on bismuth sodium titanate (Bi0.5Na0.5TiO3, BNT) and barium zirconate titanate (Ba(Zr0.07Ti0.93)O3, BZT) were prepared via a multi-step solid-state reaction process. The BNT–BZT with CuO dopant ceramics sintered at 1150–1180 °C for 2 h in air showed a pure perovskite structure. SEM images reveal that a small amount of CuO (<2 mol%) play a significant role on the microstructure to improve its sintering attributes, while it will degrade when the dopant is added beyond 2 mol%. The dielectric and piezoelectric properties of CuO-doped BNT–BZT ceramics were evaluated. At room temperature, the sample doped with 2 mol% CuO shows quite good properties such as a high piezoelectric constant (d33 ∼156.5 pC/N) and a high electromechanical coupling factor (kt ∼52%). The depolarization temperature increased dramatically and the maximum permittivity temperature decreased slightly.