Influence of Cr doping on the phase composition of Cr,Ca: YAG ceramics by solid state reaction sintering

In the present work, the influence of Cr and Ca co‐additives on the phase formation under conditions emulated the real sintering process of Cr 4+ : YAG ceramics is studied. The XRD analysis of the treated samples revealed the difference in formation rates of intermediate phases between the samples with and without the Cr 2 O 3 additive. The formation of intermediate phases in the solid‐state reaction between Y 2 O 3 and Al 2 O 3 is observed to shift toward higher temperatures (ie, toward the stage of fast shrinkage) if the mixture of Cr 2 O 3 and CaO is added. The reason for such shift is the appearance of new intermediate, which contains Cr 4+ ions in perovskite structure, as has been established by optical absorption and luminescent investigations. It is found that the Cr,Ca: YAG ceramics prepared by vacuum solid state reaction sintering at 1750°C, 10 hours possesses better optical transparency than Ca: YAG ceramics prepared under the same conditions.