Synthesis, Photoluminescence Properties and Energy Transfer Studies of Color-Adjustable Casrsio4:Ce3+,Li+,Mn2+ Phosphors

A series of color tunable phosphors CaSrSiO4:Ce3+,Li+,Mn2+ were synthesized by the traditional high temperature solid-state method. The as-prepared CaSrSiO4:Ce3+,Li+ phosphors exhibit a broad excitation band ranging from 250 to 400nm and give a blue emission band centered at 450nm. When Mn2+ ions are codoped for the fabrication of CaSrSiO4:Ce3+,Li+,Mn2+ phosphors, another new red-emitting peak appears at near 650nm corresponding to the spin-forbidden 4T1(4G)–6A1(6S) transition of the Mn2+ ions. By adjusting the relative concentration of the Ce3+ and Mn2+ ions, the CIE chromaticity coordinate can be modulated from (0.156, 0.106) to (0.224, 0.211) owing to the energy transfer from Ce3+ to Mn2+ ions. The dipole–quadrupole interaction predominates in the energy transfer mechanism. The temperature dependent photoluminescence properties prove that the CaSrSiO4 host has a good thermal stability. These results indicate that CaSrSiO4:Ce3+,Li+,Mn2+ samples show tunable blue/red dual-wavelength emission depending on the codoped ions, which might have potential applications in the white light emitting diodes (wLEDs) and functional sunlight spectrum conversion device as greenhouse for green agriculture.