Red-Emitting Phosphor Ca2MgSi2O7: Sm3+, Eu3+ for UV White Light-Emitting Diodes

In this research, a series of Ca2MgSi2O7: 2% Sm3+, x% Eu3+ (x=4, 5, 6, 7, 8) red phosphors were synthesized using the high-temperature solid-phase method. The phase and luminescence properties of the samples were investigated using an X-ray diffractometer and a photoluminescence spectrometer. The results showed that the synthesized samples were of pure phase, and the introduction of small amounts of Sm3+ and Eu3+ had no significant impact on the crystal structure of the phosphors. It is observed from the phosphor spectra that the co-doped samples exhibited intense red-light emission corresponding to that of Eu3+ at 613 nm when excited at the strongest excitation peak of Sm3+ (401 nm); here, the emission peak intensity of Eu3+ increased by a factor of 5.3. It is found that resonant nonradiative energy transfer occurs from Sm3+ to Eu3+ in the sample, and the energy transfer efficiency reaches up to 44%. The calculated critical distance for energy transfer is 16.117 Å and the concentration interrupt mechanism is an electric dipole-dipole (d-d) interaction. The color coordinates of the samples are all located in the red region (0.6319, 0.3676) with a color purity of ~ 89.3%. The samples exhibited thermal stability of up to 68.6% of that at room temperature when heated to 150˚C . The LED samples packaged with the phosphors emitted warm white-light with a color temperature (CCT) of 5553 K and a color rendering index (Ra) of 84.8. The magnesium yellow feldspar silicate phosphor is suitable as the red component in white LED trichromatic phosphors and has potential applications in solid-state lighting.