Tunable Emission Phosphor Ca0.75Sr0.2Mg1.05(Si2O6):Eu2+, Mn2+: Luminescence and Mechanism of Host, Energy Transfer of Eu2+ → Mn2+, Eu2+ → Host, and Host → Mn2+

A series of Ca0.75Sr0.2Mg1.05(Si2O6) (CSMS):xEu(2+), yMn(2+) phosphors were synthesized by a high temperature solid state reaction technique in a reducing atmosphere (1250 degrees C, 4 h). Under excitation of 270 nm, the emission spectrum of CSMS host is characterized by a broad band with two distinct emission peaks (453 and 580 nm), tailing on the energy side from approximately 350 to 800 nm. Thus, there is an orange-yellow emission in CSMS host. The different trap depths of thermoluminescence spectra (E-1 = 0.6453 eV, E-2 = 0.8271 eV) are measured and these traps will fade away when Eu2+ or Mn2+ ions are doped. In addition, the blue-shift, red-shift, and intensity changes of temperature dependence emission spectra in Ca0.75Sr0.2Mg1.05(Si2O6) host are observed with higher temperature. For Eu2+ single doped CSMS, which has an obvious absorption in the near-ultraviolet and blue region with a wide band of excitation spectrum ranging from 200 to 450 nm monitored at 453 nm. And the emission spectrum presents an obvious red shift phenomenon. Mn2+ single-doped CSMS presents the weak emission intensity at 680 nm with the excitation of 415 nm. For Eu2+ and Mn2+ codoped, the energy transfer of Eu2+ -> Mn2+, Eu2+ -> host, and host -> Mn2+ can be demonstrated, and there should be a blue-white emission in CSMS:0.03Eu(2+), 0.02Mn(2+) with CIE (0.2682, 0.2056). In short, the CSMS host presents a good application prospect in near-ultraviolet trichromatic field of white LEDs, and the luminescence properties of CSMS:xEu(2+), yMn(2+) phosphors are particularly worthy of academic investigation.