Transparent Nd:YAG Ceramics Fabricated Using Nanosized γ‐Alumina and Yttria Powders

Neodymium (Nd):Y 3 Al 5 O 12 (YAG) ceramics of excellent transparency have been fabricated by solid‐reactive sintering, using nanosized γ‐Al 2 O 3 and Y 2 O 3 powders as the starting materials. Reaction sequences and sintering behaviors of the powder mixture were characterized by X‐ray diffractometry and dilatometry. One feature of the solid reactions involving γ‐Al 2 O 3 is the occurrence of hexagonal YAlO 3 , which is unstable and transforms to perovskite YAlO 3 (YAP) upon further heating. Because of the high reactivities of the starting nanopowders, a complete conversion of the powder mixture to YAG has been achieved by heating at 1300°C for 4 h, via Y 4 Al 2 O 9 , hexagonal YAlO 3 , and YAP phases. In‐line transmittances of the 1.5 at.% Nd:YAG ceramics (doped with 0.5 wt% of tetraethyl orthosilicate) at 700 nm are 81.0% and 65.7% after vacuum sintering at 1700° and 1600°C for 5 h, respectively.