The influence of Pb(Mg1/3Nb2/3)O3 content on the piezoelectric and dielectric properties of PMMN-PZT system near the MPB

Pb(Mg1/3Nb2/3)O-3-Pb(Mn1/3Nb2/3)O-3 -PbZrO3-PbTiO3(PMMN-PZT) quaternary piezoelectric ceramics with the various contents of Pb(Mg1/3Nb2/3)O-3 (PMN), which locate in the vicinity of the MPB, were fabricated. The phase structure of the system was delineated by X-ray diffraction analysis. The piezoelectric and dielectric properties were also measured. Experimental results reveal that the MPB coexisting tetragonal and rhombohedral phases in the present system has a broad composition region from 0.10 to 0.14mol% PAIN. The piezoelectric coefficient and electromechanical coupling factor increase with increasing PMN and reach the maximum values at 12mol% PMN, then decrease remarkably with further PMN addition, whereas the variation of Qm with PMN addition shows the opposite trend. The dielectric constant also reaches the maximum value at 12mol% PMN. It is found that compared with the as-sintered samples, the dielectric constant of the poled samples in tetragonal phase increases, while there are contrary results in rhombohedral phase. The variation of dielectric properties reflects the transition from tetragonal phase to rhombohedral phase.