Investigations on the photoluminescence spectra and its defect-related nature for the ultraviolet transmitting fluoride-containing phosphate-based glasses

Abstract

Two types of fluoride-containing phosphate-based glasses were prepared under the reducing and ambient air atmosphere, respectively. And the interrelation between the micro-defects and luminescence for these glasses was investigated by studying their absorption, photoluminescence emission (PL) and excitation (PLE) spectra as well as electron spin resonance (ESR) spectra. The emission spectra under the excitation at 351nm and the excitation spectra by monitoring the emission wavelength at 433nm, 454nm, 505nm, 645nm and 780nm, together with the absorption spectra of these two types of glasses were investigated through Gaussian peak fitting method. Their photoluminescence spectra exhibit a general character with a broadband emission at around 430nm and a minor band at around 645nm. The photoluminescence excitation spectra and absorption spectra indicate that the Gaussian peak fitting of the emission spectra with the maximum at about 433, 455, 505 and 645nm, respectively, are closely associated with phosphate-related oxygen hole center defects and fluorine-related color centers. In addition, the emission and excitation spectra of the glass samples after the thermal treatment process in hydrogen atmosphere manifest that the reducing conditions promote the formation of phosphate-related oxygen hole center defects, oxygen related hole center defects and fluorine-related non-paramagnetic color centers as well as PO43− defects, while decrease the concentration level of Fe3+ and PO32− defects. The investigations on the glasses' photoluminescence properties and their changes with the glass melting and thermal treatment atmosphere will promote the further development in preparation technology of the fluoride-containing phosphate-based glasses.