Structural, dielectric, and piezoelectric properties of mn-doped BaTiO ₃-Bi(Mg_1/2Ti_1/2)O₃-BiFeO ₃ ceramics

Mn-doped (0.9 - x)BaTiO₃-0.1Bi(Mg_1/2Ti _1/2)O₃-xBiFeO₃ (x = 0.6, 0.7, and 0.8) ceramics were studied as candidate lead-free piezoelectric materials. The crystal structures were a pseudo-cubic perovskite at x = 0.6, a rhombohedral perovskite at x = 0.8, and a mixture of the pseudocubic and rhombohedral perovskite at x = 0.7. The Curie temperature was found to be 470 °C at x = 0.6 and more than 600 °C at x = 0.7 and 0.8. A strong pinning of domain walls was observed for high-field responses at x = 0.7 and 0.8, which was relaxed by high-temperature annealing and subsequent quenching. Piezoelectric properties increased with decreasing x, and the small-field piezoelectric constants d₃₃ and d₃₁ were 94 and 31 pC/N at x = 0:6, respectively.