Effects of doping cations on the densification and microstructure of flash-sintered alpha-Al2O3

The effects of dopants with different valences on the flash sintering behavior of alpha-Al2O3 are investigated. The results indicate that regardless of their valence and ionic radius, all the tested dopants reduce the onset tem-perature more effectively compared to undoped Al2O3. Interestingly, the relative density and grain size of the flash-sintered samples exhibit an inverse linear relationship. The data for the samples doped with non-trivalent cations fall on a different line than those for the samples doped with trivalent cations and the undoped samples. Dopants have an effect on the flash sintering behavior of Al2O3 because flash sintering increases the solubility of the dopants in alumina, creating more point defects, and thereby increasing the electrical conductivity of the material. The mechanisms for point defect generation in trivalent and non-trivalent dopants are different.