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

A new Ce3+-activated oxyfluoride phosphor Sr2.475La0.5Ce0.025AlO4.5F0.5 (LSAF: Ce3+) was prepared by high temperature solid-state synthesis procedure. The valence state variation of cerium ion in Sr2.475La0.5Ce0.025AlO4.5F0.5: ywt% SiO2 (LSSAF: Ce3+) and the enhancement of photoluminescence regulated by SiO2 addition were experimentally investigated. The self-reduction phenomena from Ce4+ to Ce3+ in LSSAF: Ce3+ samples was observed to be featured in the typical 5d→4f yellow-green transition of Ce3+ ion upon firing in high purity N2 and the LSSAF: Ce3+ prepared in 8% H2/N2 atmosphere exhibits an increase of photoluminescence intensity by 175% as the amount of SiO2 addition gets to be around 2.0 wt%, owing to spontaneous charge compensation and promotion of reduction from Ce4+ to Ce3+ upon SiO2 addition. The luminous intensity and emission band can be adjusted to a desired value due to the partial replacement of Al3+ by Si4+. The results demonstrate a flexible tuning means of luminescence for this Ce3+-activated oxyfluoride phosphor by simply adding SiO2.