Microstructure, Piezoelectric, and Ferroelectric Properties of BZT-Modified BiFeO3-BaTiO3 Multiferroic Ceramics with MnO2 and CuO Addition

A new lead-free piezoelectric ceramic, 0.67BiFeO 3 -0.33BaTiO 3 - x Bi(Zn 0.5 Ti 0.5 ) O 3 + 0.0035MnO 2 + 0.004CuO, was prepared through the solid-state reaction route. The ceramic was sintered in the 950–990°C range. In this paper, the crystal structure of the sample is pure perovskite structure with a pseudo-cubic structure in the range of x = 0–0.05, and does not change greatly with the increase of x . The grain size increases first and then decreases with the increase of x . The addition of Bi(Zn 0.5 Ti 0.5 ) O 3 (BZT) promoted the grain growth of the sample. The piezoelectric constant reached the maximum value of d 33 = 188 pC/N, electromechanical coupling coefficient k p = 0.301 and the remanent polarization P r = 61.20 μ C/cm 2 at x = 0.03. It has a high Curie temperature of T c = 420°C. On the other hand, the depolarization temperature reaches the maximum value, T d = 426°C, at x = 0. A small amount of BZT doping can improve the piezoelectric, dielectric, and ferroelectric properties of the samples. Therefore, this material can be considered as a promising lead-free piezoelectric ceramic material in the application field of high-temperature materials.