Light emission during electric field-assisted sintering of electroceramics

Electric field-assisted sintering has been shown to occur in ion, electron conducting as well as in insulating polycrystalline ceramics. Considerable linear shrinkage with microstructure control at temperatures lower than the conventionally utilized has been attained mainly in oxide ion conducting zirconia-based solid electrolytes. Some mechanisms, based on localized Joule heating and enhancement of defects diffusion, have been set forth to explain the sudden volume reduction in those ceramics. The results here reported contribute to the understanding of what happens during electric field-assisted sintering, by evidencing the occurrence of light emission simultaneously to the quasi instantaneous specimen shrinkage. An experimental setup with an optical fiber inserted in a dilatometer furnace allowed for light emission detection simultaneously to the electric current pulse in zirconia-yttria and also in tin dioxide specimens upon electric field-assisted sintering.