EFFECTS OF PBO CONTENT ON THE MICROSTRUCTURE AND DIELECTRIC-CONSTANT OF 0.8PB(ZN1 3NB2/3)O-3-0.1BATIO(3)-0.1PBTIO(3)/

The microstructure and the dielectric constant of 0.8Pb(Zn1/3Nb2/3)O-3 -0.1BaTiO(3)-0.1PbTiO(3) (mol fraction) change considerably with the P bO content. A single perovskite phase was observed to form in specimen s with 0.25 or 0.5 wt% PbO deficiency. When the PbO content increased above these values, a liquid phase formed and was present between pero vskite grains. As the level of PbO decreased in the specimens, on the other hand, a pyrochlore phase and a ZnO phase formed, as second phase s. The pyrochlore grains were sometimes much larger than the perovskit e grains. The densification was considerably suppressed with decreasin g PbO content. The dielectric constant showed a maximum of 22,000 in t he specimen with 0.5 wt% PbO deficiency The presence of a second phase and the reduction in the sintered density reduced the dielectric cons tant considerably. The liquid phase, however, was found to be more har mful than the pyrochlore and ZnO phases to the dielectric constant of the material.