Applying an alternating current to strontium titanate minimizes the change in oxidation state caused by flash sintering.

This study estimated the amount of oxygen deficiency in SrTiO 3 polycrystals that were flash sintered under direct current (DC) and alternating current (AC) electric fields, mainly by using the fine structural change of the Ti L 23 -edges collected by electron energy-loss spectroscopy. The DC electric field corresponded to formation of the maximum amount of oxygen deficiency at approximately δ = 0.07 as SrTiO 3−δ , which corresponds to a lattice expansion of roughly 0.1% as a lattice constant of SrTiO 3. Furthermore, the oxygen deficiency was distributed unevenly. The formation of dislocation networks in DC-flash-sintered SrTiO 3 polycrystals might be related to the lattice strain field caused by this nonuniform oxygen deficiency. In contrast, an AC electric field did not correspond to the oxygen deficiency of SrTiO 3 , which is similar to the results in thermally sintered SrTiO 3 polycrystals. [ABSTRACT FROM AUTHOR]