A new dual-emission phosphor Ca ₄Si ₂O ₇F ₂:Ce ^{3 +}, Mn ^{2 +} with energy transfer for near-UV LEDs

Ce ^{3 +} and Mn ^{2 +} co-doped Ca ₄Si ₂O ₇F ₂ phosphors have been synthesized by high temperature solid state reaction and their luminescence properties are investigated. The effect of Ce ^{3 +} concentration on the emission intensity of Ca ₄Si ₂O ₇F ₂: Ce ^{3 +} is studied, and the emission intensity reaches a maximum at 4% Ce ^{3 +}. Energy transfer from Ce ^{3 +} to Mn ^{2 +} is observed. The emission spectra of the phosphors show a blue broad band at 460 nm of Ce ^{3 +} and a yellow band at 580 nm of Mn ^{2 +}, originate from the allowed 5d → 4f transition of the Ce ^{3 +} ion and the ⁴T _1g( ⁴G) → ⁶A _1g( ⁶S) transition of the Mn ^{2 +} ion, respectively. Results indicate that the varied emitted color from blue to yellow can be achieved by tuning the relative ratio of the Ce ^{3 +} to Mn ^{2 +} ions based on the principle of energy transfer. We have demonstrated that Ca ₄Si ₂O ₇F ₂: Ce ^{3 +}, Mn ^{2 +} phosphors can be a promising candidate for a color-tunable phosphor applied in a near-UV White light emitting diodes.