Structural and composition analysis of Apex™ and Foturan™ photodefinable glasses

Little is known about photostructurable glasses when compared to quartz and the other glass families. This article investigates optical and thermal behavior of the two commercially produced Apex (TM) and Foturan (TM) photosensitive glasses in relation to their composition. A composition analysis is performed on the two glasses using Rutherford backscattering spectrometry, and UV spectroscopy. Cerium and silver were found to exist at higher concentrations in Foturan than in Apex glass. Difference in transmission in the 240-340 nm window is mainly attributed to the different concentrations of cerium and silver in the glasses. Infrared transmission in the range of 2.7-5.0 mu m is improved following an annealing process. Structural stability over a different range of temperatures in the two photosensitive glasses is investigated, and is attributed to the silica content at the expense of lithium oxide. Raman spectroscopy shows that the UV-exposed-then-baked photosensitive glass, results in the formation of a uniform crystalline-phase lithium metasilicate with a preponderantly Q(2) species.