HOST-ASSOCIATED LUMINESCENCE FROM YAG OPTICAL CERAMICS UNDER GAMMA-EXCITATION AND OPTICAL-EXCITATION

The host-associated luminescence of highly dense transparent YAG ceram ic material is characterized and compared to that of a single crystal. The UV emission from the ceramic shows a red shift of almost 100 nm f rom its position in the single crystal, along with major differences i n excitation spectrum. The disparities suggest that the two emissions have different origins in the respective materials, probably related t o the differences in microstructure and preparation conditions. Altera tions in the shape of the intense absorption associated with the band- to-band transition reflect profound changes in carrier distribution in the boundary region as well as a high population of defects incorpora ted during the grain growth. (C) 1998 Published by Elsevier Science B. V. All rights reserved.