Dielectric and electromechanical properties of PbNi1/3Nb 2/3O3-PbTiO3-PbZrO3 system: a processing-property study

The processing-property relationship in the system xPbNi_1/3 Nb_2/3O₃-(1-x)[yPbTiO₃-(1-y)PbZrO ₃] (PNN-PT-PZ), with 0.4⩽x⩽0.6 and 0.6⩽y⩽0.8, were investigated. Samples were processed by three different routes: direct reaction of the oxide constituents, Columbite precursor process, and the PNN-perovskite mixing route. Calcination and sintering studies were carried out at different temperatures for 1-8 hours under controlled PbO atmospheres. Phase evolution was monitored by powder x-ray diffraction (XRD). Scanning electron microscopy (SEM) was used for microstructural characterization. Maxima in the dielectric and electromechanical properties were obtained for samples with x=0.5 and y=0.7 that were sintered at 1200°C. At room temperature, the highest dielectric constant was 6400 with a dissipation factor of 2%. These samples exhibit strong electromechanical coupling, k_t=58 and k_p=77%. The piezoelectric charge coefficient (d₃₃) of an optimum composition was found to be 820 pC/N