Effect of holding time on the microstructure and properties of flash-sintered Y₂O₃-doped ZrO₂

A mixture of pure monolithic ZrO₂and Y₂O₃ powders was flash-sintered at different holding times. The results show that flash-sintering led to a rapid phase transformation: The starting monolithic ZrO₂completely transformed to tetragonal phase after the flash-sintering for as short as 10 s. Although dense samples with relatively uniform microstructures were obtained at a holding time of longer than 5 min, the holding time had no significant effect on grain size. Both the bulk and intrinsic grain-boundary conductivity increased with an increase in the holding time, indicating that flash-sintering created oxygen vacancies in both grains and grain boundaries that accumulated with an increase in the holding time.