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

摘要

Neodymium (Nd):Y_3Al_5O_(12) (YAG) ceramics of excellent transparency have been fabricated by solid-reactive sintering, using nanosized γ-Al_2O_3 and Y_2O_3 powders as the starting materials. Reaction sequences and sintering behaviors of the powder mixture were characterized by X-ray diffractometry and dilatome-try. One feature of the solid reactions involving γ-Al_2O_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℃ for 4 h, via Y_4Al_2O_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 orthosil-icate) at 700 nm are 81.0% and 65.7% after vacuum sintering at 1700° and 1600℃ for 5 h, respectively.