Effects of Sintering Aids on the Transparency and Conversion Efficiency of Cr 4+ Ions in Cr: YAG Transparent Ceramics

Tetravalent chromium‐doped Y 3 Al 5 O 12 ceramics were fabricated by solid‐state reactive sintering method using high‐purity Y 2 O 3 , α‐ Al 2 O 3 , and Cr 2 O 3 powders as the starting materials. CaO and MgO were co‐doped as the sintering aids. The effects of TEOS and divalent dopants (CaO and MgO) on the optical qualities, the conversion efficiency of Cr 4+ ions, and the microstructure evolutions of 0.1 at.% Cr 4+ : YAG ceramics were investigated. Fully dense, dark brown colored Cr 4+ : YAG ceramics with an average grain size of 3.1 μm were achieved. The in‐line transmittance of the as‐prepared ceramic at 2000 nm was 85.3% (4 mm thick), and the absorption coefficient at 1030 nm (the characteristic absorption peak of Cr 4+ ions) was as high as 3.7 cm −1 , which was higher than that of corresponding single crystals fabricated by Czochralski method.