Microstructure and electric properties of Nb doping x(Ba_0.7Ca_0.3)TiO₃–(1−x)Ba(Zr_0.2Ti_0.8)O₃ceramics

In this paper, t mol% Nb₂O₅doped x(Ba_0.7Ca_0.3)TiO₃–(1−x)Ba(Zr_0.2Ti_0.8)O₃[xBCT–(1−x)BZT–t mol% Nb₂O₅] lead-free piezoelectric ceramics were prepared successfully using a solid-state reaction technique. Firstly, the phase transition of xBCT–(1−x)BZT ceramics were investigated, and it was found that 0.47BCT–0.53BZT sample shows a rhombohedral (R)–tetragonal (T) phase transition at room temperature near Morphotropic Phase Boundary and presents better ferroelectric and piezoelectric properties compared with the other component ceramics. On this basis, the crystal structure, surface morphologies and electrical properties of the Nb₂O₅doped 0.47BCT–0.53BZT ceramic were studied in detail. It was found the grain size increases monotonously and the microstructure become more denser and homogeneous when Nb-doping concentration increases above t = 0.3, and a maximum strain value of 0.132% was obtained at E = 20 kV/cm. Additionally, the excellent electric properties with a high remanent polarization (P_r = 8.3 μC/cm²), a low coercive field (E_c = 1.55 kV/cm) were also obtained on 0.47BCT–0.53BZT–0.3 mol% Nb₂O₅lead-free ceramics, which is promising for application in lead-free practical applications.