Piezoelectric properties of Pb(Mn1/3Nb2/3)O3–PbZrO3–PbTiO3 ceramics with sintering aid of 2CaO–Fe2O3 compound

Since the electromechanical devices move towards enhanced power density, high mechanical quality factor (Qm) and electromechanical coupling factor (kp) are commonly needed for the high powered piezoelectric transformer with Qm≥2000 and kp=0.60. Although Pb(Mn1/3Nb2/3)O3–PbZrO3–PbTiO3 (PMnN–PZ–PT) ceramic system has potential for piezoelectric transformer application, further improvements of Qm and kp are needed. Addition of 2CaO–Fe2O3 has been proved to have many beneficial effects on Pb(Zr,Ti)O3 ceramics. Therefore, 2CaO–Fe2O3 is used as additive in order to improve the piezoelectric properties in this study. The piezoelectric properties, density and microstructures of 0.07Pb(Mn1/3Nb2/3)O3–0.468PbZrO3–0.462PbTiO3 (PMnN–PZ–PT) piezoelectric ceramics with 2CaO–Fe2O3 additive sintered at 1100 and 1250 °C have been studied. When sintering temperature is 1250 °C, Qm has the maximum 2150 with 0.3 wt.% 2CaO–Fe2O3 addition. The kp more than 0.6 is observed for samples sintered at 1100 °C. The addition of 2CaO–Fe2O3 can significantly enhance the densification of PMnN–PZ–PT ceramics when the sintering temperature is 1250 °C. The grain growth occurred with the amount of 2CaO–Fe2O3 at both sintering temperatures.