Preparation and upconversion luminescence properties of Yb3+/Tb3+/Ho3+ tri-doped phosphate glasses

In this study, Yb3+/Ho3+, Yb3+/Tb3+ co-doped, and Yb3+/Ho3+/Tb3+ tri-doped phosphate glasses have been prepared by the high-temperature melting method using P2O5 as the base material, and these phosphate glasses are characterized as non-crystalline structures by X-ray diffraction. Under 980 nm excitation, highly efficient blue (489 nm), green (545 nm), and red (661 nm) upconversion luminescences can be observed in this glass system, which are attributed to Tb3+: D-5(4)-> F-7(6), Tb3+: D-5(4)-> F-7(5), and Ho3+: F-5(5)-> I-5(8) radiative transitions, respectively. The upconversion emission intensity and excitation power dependence analysis reveal that the blue and green light emissions are three-photon processes, while red light emission is a two-photon process. White light emission can be achieved by adjusting the doping concentration of rare-earth ions in the Yb3+/Ho3+/Tb3+ tri-doped phosphate glasses. The CIE chromaticity coordinates of 2Yb(3+)/0.1Ho(3+)/0.4Tb(3+) tri-doped phosphate glass (0.39, 0.39) under 980 nm excitation are relatively close to those of the standard light source (0.33, 0.33), indicating the potential application of this material in the field of illumination, such as emissive displays, fluorescent lamps and fiber lasers.