Quantitative differences in the Y grain boundary excess at boundaries delimiting large and small grains in Y doped Al2O3

Abstract

The chemical excess at high angle grain boundaries in yttrium doped alumina was characterized using transmission electron microscopy and energy dispersive spectroscopy. The sample had a bimodal microstructure and one explanation for the fast growth of some grains was that they were surrounded by boundaries with a different yttrium grain boundary excess than the smaller grains. The amount of yttrium at boundaries between grains of similar and different sizes was quantified. Boundaries between smaller grains and between small grains bonded to sapphire had a mean Y excess of 1.3 atoms/nm2. The grain boundary excess of Y for boundaries delimiting large grains had either a lower Y content of 0.5 atoms/nm2 and 0.9 atoms/nm2, or a higher Y content of 1.6 atoms/nm2, consistent with the idea that these boundaries had a different composition and thus different complexions.