Cubic yttria stabilized zirconia sintering additive impacts: A comparative study

To evaluate the impact sintering additives have on the processing and performance of 8 mol% yttria stabilized zirconia (8YSZ), the 25–1525 °C sintering kinetics, phase purity, microstructure, and electrical properties of a single batch of 8YSZ powder surface-coated with 1, 3 and 5 mol% of barium, bismuth, calcium, cobalt, copper, iron, lithium, magnesium, manganese, nickel, strontium or zinc were investigated via constant heating rate dilatometry, X-ray diffraction, scanning electron microscopy, and AC impedance spectroscopy. For electrochemical applications where dense 8YSZ is required, iron was found to give the best combination of 8YSZ cubic zirconia phase stability, high oxygen ion conductivity, and enhanced densification kinetics. 5 mol% iron was found to reduce the 8YSZ sintering temperature by ~150 °C.