| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1473247 | Journal of Asian Ceramic Societies | 2013 | 6 Pages |
•Coloration of Ti-doped sapphire grown by the Flame-Fusion Method was examined.•By UV irradiation, TiAlIV+ changed into TiAlIII× and hole (h+).•The hole was trapped in VAl3−, and the resultant color center caused brown coloration.•(Ti–Fe) and (Ti–Mg) co-doping was affected to prevent the coloration by UV.
Coloration of Ti-doped sapphire grown by the Flame-Fusion Method was examined here in detail. The as-grown sapphire was slightly colored with pink caused by Ti3+. After annealing in the air, the pink color faded away because Ti3+ oxidized to Ti4+. The colorless sapphire was colored anew into brown by ultraviolet (UV) irradiation. This coloration was discussed based on some defects in Al2O3. By UV irradiation, TiAlIV+ changed into TiAlIII× and hole (h+). The hole was trapped in VAl3−, and the resultant color center caused brown coloration. In order to prevent the valence change, co-doping with (Ti–Fe) and (Ti–Mg) was attempted. Then, the brown coloration decreased successfully.
