Introduction of silver into a silicate glass often leads to reduction and coloration. The electron required for silver reduction is extracted from a nonbridging oxygen atom. The use of high-field-strength ions limits the number of nonbridging oxygens and silver reduction.
© 1992 Optical Society of America
Roger Araujo, "Colorless glasses containing ion-exchanged silver," Appl. Opt. 31, 5221-5224 (1992)