Processing and properties of PMMN–PZT quaternary piezoelectric ceramics for ultrasonic motors

Piezoelectric Pb(Mg1/3Nb2/3)O3–Pb(Mn1/3Nb2/3)O3–PbZrO3–PbTiO3 (PMMN–PZT) quaternary ceramics with various contents of Pb(Mn1/3Nb2/3)O3 from 4 to 8 mol% were prepared. The conventional single-stage and columbite two-stage methods were compared. Columbites MgNb2O6 and MnNb2O6, and the phase structure of PMMN–PZT were examined using X-ray diffraction (XRD). The surface morphology was examined by SEM. Study on the effect of Pb(Mn1/3Nb2/3)O3 additives on dielectric and piezoelectric properties indicated that the PMMN–PZT quaternary system exhibited a high mechanical quality factor and well-situated piezoelectric properties. The optimized results of d33 (307 pC/N), Kp (0.55) and Qm (2379) were obtained at 6 mol% Pb(Mn1/3Nb2/3)O3.