Dielectric and electromechanical properties of PbNi/sub 1/3/Nb/sub 2/3/O/sub 3/-PbTiO/sub 3/-PbZrO/sub 3/ system: a processing-property study

The processing-property relationship in the system xPbNi/sub 1/3/Nb/sub 2/3/O/sub 3/-(1-x)[yPbTiO/sub 3/-(1-y)PbZrO/sub 3/] (PNN-PT-PZ), with 0.4/spl les/x/spl les/0.6 and 0.6/spl les/y/spl les/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/spl deg/C. At room temperature, the highest dielectric constant was 6400 with a dissipation factor of 2%. These samples exhibit strong electromechanical coupling, k/sub t/=58 and k/sub p/=77%. The piezoelectric charge coefficient (d/sub 33/) of an optimum composition was found to be 820 pC/N.