Effects of incubation on microstructure gradient in flash-sintered TiO2

Recent studies show that flash sintering can introduce different types of defects in various ceramics. We investigate the effects of pre-flash incubation on the microstructure of flash-sintered ceramics by comparing flash-sintered TiO2 samples under constant field (CF) and instant field (IF). The CF sample underwent an incubation period before flash sintering, while IF sample “flashed” instantaneously after the application of electric field. The CF induced a higher relative density and greater grain size than those in the IF flash-sintered specimens. Raman spectroscopy and transmission electron microscopy analyses showed that the CF sample has more types of defects, such as dislocations and stacking faults. The correlation between microstructural defects and the incubation period is discussed.