RELATIONSHIP BETWEEN PHASE-STABILITY AND CONDUCTIVITY OF YTTRIA TETRAGONAL ZIRCONIA

Impedance studies have been made on a high purity 5.15 wt% yttria (Y2O3) tetragonal zirconia polycrystalline material as a function of the cooling rate from the sintering temperature and annealing temperatures ranging between 400°C and 1350°C. Both the grain boundary and the lattice resistivities change in a complimentary fashion as a function of the cooling rate but annealing has a much more pronounced effect on the lattice resistivity. The maximum in the lattice resistivity occured for specimens annealed at about 1200°C. A substructure consisting of different tetragonal variants and solute partitioning existed within the grains of all the specimens. The degree of substructure varied with annealing temperature and the cooling rate. Increase in the lattice resistivity has been attributed to this substructure within the grains. © 1990.