Sintering and microstructure evolution of Er1.5Y1.5-xScx+yAl5-yO12 garnet ceramics with scandium in dodecahedral and octahedral sites

Abstract

The sintering behavior of scandium-containing garnet materials within the Y2O3-Er2O3-Sc2O3-Al2O3 system was investigated. Single-phase ceramic powders and optical ceramics’ samples of Er1.5Y1.5-xScxScyAl5-yO12 (x = 0.2 ÷ 1.5; y = 0.2 ÷ 0.8) were prepared. An increase of scandium content in the dodecahedral garnet site has led to a temperature decrease of the shrinkage onset and the maximum shrinkage rate, as well as vacuum sintering temperatures narrowing. The decomposition of solid solutions with a high scandium dodecahedral content, accompanied by an optical quality deterioration due to mechanical mixtures formation, has been detected. According to the SEM data, the decomposition processes are accompanied by abnormal grains growth. Optical ceramics’ samples transmission coefficients were about 80% in the visible and near-IR ranges. An unique “SAG:Er” material (Er1.5Sc1.7Al4.8O12), characterized by the minimum dodecahedral radius and the unit cell parameter compared to the known erbium-doped garnet matrixes has been obtained.