Abstract
A new color center based on a local structural and chemical change of the average borate tungstate glass matrix has been identified. The matrices of the colored glasses all had a 1:1 ratio of Li 2 B 4 O 7 and WO 3 except for glasses with x = 0. The reaction took place in air and at 1200 K in all cases, while the reaction time varied between 10 and 60 min. Subsequent to reaction, the glasses were cooled to 550 K in 1 min and then annealed in air at that temperature for 2 h. The coloration starts at a critical temperature T c = 630 K and needs latent sites. The coloration process involves a distribution of energy barriers for the migration of Li + with half-width comparable to its mean value, 2.91 eV. The achieved center concentrations are estimated to lie between 0.3 and 3 mol%. In addition, a color center has been found which is connected with Fe +3 impurities. This coloration is reversible and connected with a temperature-induced shift, 5 × 10 −4 eV/K, of the Fe-based oscillators.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
