Preparation and luminescence properties of Tb3+-Sm3+ co-doped K3Gd(PO4)2 crystalline glass ceramics

In this paper, Tb3+-Sm3+ co-doped glass ceramics with K3Gd(PO4)2 crystal phase were successfully prepared by methods of melting curing crystallization. The optimal heat treatment conditions for the samples were determined to be held for 1.5 h at 750 °C by combining differential scanning calorimeter (DSC), x-ray diffraction (XRD) and scanning electron microscope (SEM). Under this condition, glass ceramics still have a high transmittance in the range of 400∼700 nm, up to 80 %. It was calculated that the optical band gap value of glass ceramic is smaller than that of glass, indicating that the sample structure was changed by heat treatment. Fluorescence lifetime and Dexter's theory demonstrate that Tb3+ transfers energy to Sm3+. By fixing the concentration of Tb3+ and changing the doping concentration of Sm3+, the luminous color of glass ceramics can be adjusted. At 458 K, the fluorescence intensity of Tb3+ and Sm3+ decreased to 89 % and 85 % of that at 298 K. Study shows that the prepared glass ceramics have potential applications in white light emitting diodes (WLEDs).