DIELECTRIC PROPERTIES OF LEAD MAGNESIUM NIOBATE-LEAD TITANATE CERAMICS PREPARED BY MIXED-OXIDE METHOD

In this study, the (1 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (when x = 0.1, 0.3 and 0.5) ceramics were prepared from PMN and PT powders by a mixed-oxide method. The dielectric properties of the ceramics were measured as functions of both temperature (-150-400 degrees C) and frequency (100 Hz-1 MHz). The results indicated that the dielectric properties of pseudo-cubic phase 0.9PMN-0.1PT and tetragonal phase 0.5PMN-0.5PT ceramics followed that of relaxor and normal ferroelectric behaviors, respectively, while the dielectric behaviors of a near MPB phase 0.7MN-0.3PT ceramic showed a mixture of normal and relaxor ferroelectric behaviors. In addition, the Curie temperature (T-C) increased with increasing PT contents, while the diffusivity decreased. This confirmed a gradual transition from a relaxor ferroelectric behavior in 0.9MN-0.1PT to a normal ferroelectric behavior in 0.5PMN-0.5PT. The difference in dielectric behaviors was attributed to the structural symmetry of the ceramics.