Powder chemistry effects on the sintering of MgO‐doped specialty Al 2 O 3

In this work, we investigate the effects of powder chemistry on the sintering of MgO‐doped specialty alumina. The stages at which MgO influences densification of Al 2 O 3 were identified by comparing dilatometry measurements and the sintering kinetics of MgO‐free and MgO‐doped specialty alumina powders. MgO is observed to reduce the grain boundary thickness during densification using TEM . We show that MgO increases the solubility of SiO 2 in alumina grains near the boundaries using EDS . First‐principles DFT calculations demonstrate that the co‐dissolution of MgO and SiO 2 in alumina is thermodynamically favored over the dissolution of MgO or SiO 2 individually in alumina. This study experimentally demonstrates for the first time that removal of SiO 2 from the grain boundaries is a key process by which MgO enhances the sintering of alumina.