Influence of processing conditions on the morphotropic phase boundaries and ferroelectric properties of Pb(Zn/sub 1/3/Nb/sub 2/3/)O/sub 3/-Pb(Ni/sub 1/3/Nb/sub 2/3/)O/sub 3/-Pb(Zr/sub 1/2/Ti$ d1/sub /2/)O/sub 3/ solid solutions

摘要

Ceramic solid solutions within the ternary system of Pb(Zn/sub 1/3/Nb/sub 2/3/)O/sub 3/-Pb(Ni/sub 1/3/Nb/sub 2/3/)O/sub 3/-Pb(Zr/sub 1/2/Ti$ d1/sub /2/)O/sub 3/ (PZN-PNN-PZT) were synthesized via two methods: the mixed oxide method and the columbite method. Phase development of the calcined powders and the crystal structure of sintered ceramics were analyzed by X-ray diffraction. The ferroelectric properties of the ceramics were characterized by a combination of dielectric and hysteresis measurements. It was observed that for the binary systems PZN-PZT and PNN-PZT, the change in the transition temperature (T/sub m/) is nearly linear with respect to the PZT content. Ferroelectric properties were analyzed to elucidate the nature of the phase transformation and identify the impact of the processing conditions. With these data, ferroelectric phase diagrams were derived showing the transition between the pseudo-cubic relaxor behavior of PZN and PNN to the tetragonal normal ferroelectric behavior of PZT. This transition was also correlated to changes in the diffuseness parameter /spl delta//sub /spl gamma// When comparing ceramics prepared by the columbite method and the mixed oxide route, ceramics prepared by the mixed oxide method showed a lower remanent polarization P/sub r/ and a higher coercive field E/sub c/. Additionally, ceramics prepared by the columbite method displayed sharp transitions in ferroelectric properties across the MPB composition, whereas these transitions were obscured in ceramics prepared by the mixed oxide method. It is proposed that the different reaction paths influenced the degree of compositional heterogeneity in these complex perovskite solid solutions, which was clearly reflected in the nature of the phase transition.