The effect of Bi2O3 on the microstructure and electrical conductivity of ZrO2-Y2O3 ceramics

ZrO₂-Y₂O₃ ceramics with varying Bi₂O₃ contents were prepared and their microstructures and electrical conductivities investigated. The phase stability of cubic fluorite zirconia was disturbed by the introduction of Bi₂O₃ and tetragonal or monoclinic second phases appeared. The effect of the second phases on the intragrain and the grain boundary conductivities was investigated in the 300–550 C range using complex plane analysis in the frequency range of 5 Hz to 13 MHz. It showed that conductivity data could readily be interpreted in terms of possible physical models and electrical equivalent circuits. Tetragonal phases had a small positive influence on the intragrain conductivity. The grain 9boundary resistivity could be diminished by discrete monoclinic second phases which offered more conductive intergranular contacts.