Adjustable photoluminescence of a new family oxyfluoride phosphor for white light-emitting diodes through addition of SiO2

Abstract A new Ce 3+ -activated oxyfluoride phosphor Sr 2.475 La 0.5 Ce 0.025 AlO 4.5 F 0.5 (LSAF: Ce 3+ ) was prepared by high temperature solid-state synthesis procedure. The valence state variation of cerium ion in Sr 2.475 La 0.5 Ce 0.025 AlO 4.5 F 0.5 : y wt% SiO 2 (LSSAF: Ce 3+ ) and the enhancement of photoluminescence regulated by SiO 2 addition were experimentally investigated. The self-reduction phenomena from Ce 4+ to Ce 3+ in LSSAF: Ce 3+ samples was observed to be featured in the typical 5d→4f yellow–green transition of Ce 3+ ion upon firing in high purity N 2 and the LSSAF: Ce 3+ prepared in 8% H 2 /N 2 atmosphere exhibits an increase of photoluminescence intensity by 175% as the amount of SiO 2 addition gets to be around 2.0 wt%, owing to spontaneous charge compensation and promotion of reduction from Ce 4+ to Ce 3+ upon SiO 2 addition. The luminous intensity and emission band can be adjusted to a desired value due to the partial replacement of Al 3+ by Si 4+ . The results demonstrate a flexible tuning means of luminescence for this Ce 3+ -activated oxyfluoride phosphor by simply adding SiO 2 .