Intense UVC emission and upconversion in Pr-doped condensed borate glass-ceramic

Converting visible light into ultraviolet light holds immense potential, particularly in areas such as disinfection and sterilization, and the development of ultraviolet lasers. Research efforts are focused primarily on the study of powder samples, while bulk phosphors are necessary for practical applications. In this work, bulk samples of borate-based glass and glass-ceramics doped with Pr³⁺ were synthesized using melt-quenching method. X-ray powder diffraction, photoluminescence spectra, luminescence decay kinetics, and upconversion properties of the samples were investigated. Under blue light excitation Pr³⁺-doped glass and glass-ceramic samples exhibited anti-Stokes emission in the UVC/UVB spectral range, corresponding to the 4f5d → ³H_J,³F_J transitions of Pr³⁺ ions. Power-dependent studies and upconversion luminescence decay analyses confirm that excited-state absorption is the primary mechanism responsible for upconversion in both samples under pulsed laser excitation. The efficiency of UVC/UVB upconversion is enhanced in glass-ceramic compared to glass sample, but it also leads to the shift of the emission barycenter towards UVB.