Photoluminescence of sodium germanosilicate glass synthesized by melting mixture of SiO2, GeO2, and Na2CO3

Glasses with the composition (SiO2)50(GeO2)50-x(Na2O)x (x = 0, 20-40) were synthesized at 1600 °C by melting in air, and their photoluminescence properties were investigated. Furthermore, the formation of non-bridging oxygens (NBOs) and oxygen vacancies in the (SiO2)50(GeO2)50-x(Na2O)x glasses was examined using X-ray photoelectron spectroscopy. In contrast to the violet-blue emission of the (SiO2)50(GeO2)50 glass, the (SiO2)50(GeO2)20(Na2O)30 glass exhibits a quasi-white emission under ultraviolet light. The internal quantum efficiency of the (SiO2)50(GeO2)20(Na2O)30 glass at an excitation wavelength of 250 nm was 37%. It was confirmed that the number of NBOs increases with the addition of Na2O in (SiO2)50(GeO2)50 glass.