Photoluminescence Properties of Novel Far-Red Emission Ca3Gd2W2O12:Mn4+ Phosphor

A series of Ca3Gd2W2O12:Mn4+ far-red phosphors were successfully synthesized by high temperature solid state reaction. The crystal phases and morphology of the powders were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The luminescent properties of the samples with varying Mn4+ concentrations were investigated, and the result indicates that prepared phosphor Ca3Gd2W2O12:Mn4+ can be excited by ultraviolet light and exhibit intense far red emission at 710 nm. The optimum doping concentration of Mn4+ is about 0.2 mol %. The internal quantum efficiency of Ca3Gd2W2O12:Mn4+ phosphors are 58.5%. In addition, the mechanism of luminescence is also analyzed by using Tanab-Sugano energy level diagram. The thermal stability of samples have been researched and discussed. Finally, a far-red LED was fabricated by combining a 365 nm near-ultraviolet InGaN chip with Ca3Gd2W2O12:Mn4+ phosphor. All the results indicated that Ca3Gd2W2O12:Mn4+ as an excellent phosphor can be applied to far-red LED lamp and it has potential applications in plant growth.