Synthesis and photoluminescence enhancement of Ca3Sr3(VO4)4:Eu3+ red phosphors by Sm3+ doping for white LEDs

A new type of red-emitting Eu3+ and Sm3+ co-doped Ca3Sr3(VO4)(4) phosphor was synthesized by the combustion method. The photoluminescence properties and microstructure were investigated by photoluminescence spectroscopy, X-ray powder diffraction, and scanning electron microscopy. All samples were found to match perfectly with the rhombohedral structure and belong to the R3c space group. The photoluminescence emission intensity of the optimal phosphor Ca3Sr3(VO4)(4):0.05Eu(3+), 0.09Sm(3+) at 619 nm was significantly enhanced compared with those of Ca3Sr3(VO4)(4):Eu3+ samples and commercial Y2O3:Eu3+ at an excitation wavelength of 393 nm, as a result of the energy transfer from Sm3+ to Eu3+. The energy transfer process between Sm3+ and Eu3+ is discussed and interpreted by considering the energy level diagram. Furthermore, the CIE chromaticity coordinate of Ca3Sr3(VO4)(4):0.05Eu(3+), 0.09Sm(3+) was closer to the standard red-emitting point (x = 0.67, y = 0.33) than Y2O3:Eu3+. The luminescence performance of Ca3Sr3(VO4)(4):Eu3+, Sm3+ upon excitation by near-UV radiation makes it a promising red phosphor for manufacturing white-light-emitting diodes.