Enhanced broadband excitable near-infrared luminescence in Ce3+/Yb3+ codoped oxyapatite based glass ceramics

Oxyapatite-containing glass ceramics coactivated with Ce3+ and Yb3+ were prepared with reducing Al-powder. The precipitation of Ba4La6(SiO4)(6)O polycrystals exhibiting lattice contraction due to their preferential enrichment of rare earth ions was confirmed by crystallization and microstructural analysis. Upon 366 nm excitation, intense near infrared emission around 1 mu m due to Yb3+ : F-2(5/2) -> F-2(7/2) transition was achieved in glasses and glass ceramics, indicating the occurrence of energy transfer from Ce3+ to Yb3+. The underlying mechanisms could be described as a single-step indirect process via intermediate Ce4+-Yb2+ charge transfer state, most likely involving Ce3+ ions on La3+ neighbor sites. An optimal enhancement as much as three folds in near infrared emission was obtained after crystallization, which probably resulted from the partition of Ce3+ and Yb3+ into crystals. The results show that glass ceramic may be a promising candidate applicable for the development of high-efficiency c-Si solar cells.