Piezoelectric characteristics of low temperature sintering Pb(Mn1/3Nb2/3)O3–Pb(Ni1/3Nb2/3)O3–Pb(Zr0.50Ti0.50)O3 according to the addition of CuO and Fe2O3

In this study, in order to develop the composition ceramics for low temperature sintering multilayer piezoelectric actuator and ultrasonic vibrator, Pb(Mn1/3Nb2/3)O3–Pb(Ni1/3Nb2/3)O3–Pb(Zr0.50Ti0.50)O3 (abbreviated as PMN–PNN–PZT) ceramics were fabricated using Li2CO3 and Na2CO3 as sintering aids, their structural, piezoelectric and dielectric characteristics were investigated according to the addition of CuO and Fe2O3, respectively. The addition of CuO and Fe2O3 improved sinterability and density and suppressed secondary phase. In the CuO added PMN–PNN–PZT ceramics, mechanical quality factor (Qm) was improved due to the acceptor doping effect. However, in the Fe2O3 added PMN–PNN–PZT ceramics, it seemed that Fe2O3 reacted as softner because dielectric constant (ɛr) and electromechanical coupling factor (kp) were significantly increased by the increase of grain size and sinterability. At 0.2 wt.% CuO added specimen sintered at 900 °C, density, electromechanical coupling factor (kp), mechanical quality factor (Qm), dielectric constant (ɛr) and piezoelectric constant (d33) showed the optimum value of 7.856 g/cm3, 0.60, 1130, 1018 and 346 (pC/N), respectively. At 0.2 wt.% Fe2O3 added specimen sintered at 900 °C, density, electromechanical coupling factor (kp), mechanical quality factor (Qm), dielectric constant (ɛr) and piezoelectric constant (d33) showed the optimum value of 7.850 g/cm3, 0.62, 975, 1275 and 377 (pC/N), respectively. Taking into consideration above piezoelectric properties, it was concluded that PMN–PNN–PZT ceramics using 0.2 wt.% Fe2O3 as additive showed the piezoelectric characteristics suitable for low loss and low temperature sintering multilayer piezoelectric actuator application.