Effective Red Compensation of Sr2SiO4 : Dy3+ Phosphor by Codoping Mn2+ Ions and Its Energy Transfer

Mn2+ ions codoped Sr2SiO4 : Dy3+ phosphors were prepared by the solid-state reaction method using NH4Cl as the flux. Their phase compositions, photoluminescence properties, and the energy transfer process were systematically investigated. All Mn/Dy codoped powders were α′-Sr2SiO4. The codoping concentration range of Mn2+ was ≤4.0 mol% to keep the structure undamaged. The broad red emission of Mn2+ centered at 647 nm in Sr2SiO4 : Mn, Dy powders, which effectively compensated the red emission of Sr2SiO4 : Dy3+ phosphor. The CIE chromaticity coordinates dramatically changed from (0.310, 0.340) to (0.332, 0.326) due to the red enhancement via the energy transfer from Dy3+ to Mn2+. This energy transfer is realized by the exchange interaction. But the luminescence quenching of Sr2SiO4 : Dy, Mn phosphor was mainly caused by the electric multipoles interaction. The concentration optimized (Sr0.96, Mn0.02, Dy0.02)2SiO4 phosphor with high and almost pure white emission has great potential to act as a single-matrix white phosphor for white LEDs