Surface Segregation of Aluminum (Spinel Precipitation) in MgO Crystals

Abstract

MgO single crystals containing 0.006 and 0.187 wt% Al in solid solution at 1850°C were quenched and slow cooled. Analysis of the Al distribution near the surface with ion microprobe mass analysis indicated an increased Al concentration and near‐surface precipitation within a region × to 4 μ thick in the slow‐cooled samples and a much smaller enhanced concentration in the region 0.1 to 0.2 μ from the surface in the quenched samples.