Preparation of red-emitting phosphor (Y,Gd)BO3:Eu3+ by high temperature ball milling

The red-emitting phosphor (Y,Gd)BO3:Eu3+ was prepared by high temperature ball milling in order to improve the color purity and decrease the calcining temperature. The phosphor was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and luminescence spectra. The results showed that the phosphor(Y,Gd)BO3:Eu3+ could be obtained at 600 °C, i.e. at a much lower temperature in contrast to conventional solid state reaction. The phosphor can be effectively excited by VUV radiation at 147 nm. In its emission spectrum, the strongest peak at 628 nm correlating to red emission was ascribed to the forced electric dipole transition 5D0→7F2 of Eu3+ ions. Its chromaticity coordinates (CIE) were calculated to be x=0.65, y=0.35. Significantly, the intensity ratio of Y0.65Gd0.1Eu0.25BO3 phosphors of the red (5D0→7F2) to the orange (5D0→7F1) transition (R/O value) is 2.39, which is higher than 2.15 of the phosphor prepared by solid state reaction. The color purity was significantly improved. The particles with narrow distribution range and spherical morphology were approximately 200 nm in size. The luminescent properties of the (Y,Gd)BO3:Eu3+ sample with 25 mol% doping concentration of Eu3+ were optimal. Therefore, high temperature ball milling is of help to (Y,Gd)BO3:Eu3+ phosphor for improving the color purity and decreasing the calcining temperature in the future applications.