Structure and upconversion luminescence properties of Pr3+-doped Y2Si2O7 phosphor prepared by different methods

Ultraviolet-C (UVC) light shows important application prospects in disinfection, disease phototherapy, cancer photodynamic therapy, etc. Here, a novel UVC upconversion phosphor δ-Y2Si2O7:Pr3+ with excellent optical properties was successfully prepared by the high-temperature solid-state reaction method and the sol-gel method. The XRD results clarified the law of phase transition from the β-/γ-Y2Si2O7 to the δ-Y2Si2O7 phase. The diffuse reflection spectra of phosphors prepared by two different methods exhibited two obvious absorption bands related to the 3H4 → 3P2 and 3H4 → 1D2 transitions of Pr3+ ions. And the values of the band gap were estimated by diffuse reflection spectra, which are in good agreement with the value calculated by DFT. Under the excitation of 460 nm laser, two emission peaks corresponding to the 4f5d → 3H4 and 4f5d → 3H5 transitions of Pr3+ ions were discovered at ∼247 nm and ∼258 nm in the range of 230–280 nm. Additionally, the phosphor prepared by the sol-gel method has a higher emission intensity than the phosphor prepared by the high-temperature solid-state reaction method. With the help of temperature-dependent emission spectra, the phosphor prepared by two methods demonstrated outstanding thermal stability up to 150 °C, and the luminescent intensity at 150 °C remained 86.8% and 87.9% of that at ambient temperature, respectively. The results mentioned above suggest that the Y2Si2O7:Pr3+ phosphor may have potential applications in the field of disinfection.