The Difference Infrared Spectra of Titanium-Containing Vitreous Silica

Abstract

Vitreous silicas containing up to 10% titania are of significant commercial importance because of their low thermal expansions. Instrumental techniques are being developed to determine the structure of the titanium groups in these glasses in order to relate their reduced thermal expansitivities with structural properties. Amosov, Zakharov, and Yudin have investigated both the ESR and optical spectra of titanium-containing quartz glasses. Tobin and Baak have observed the Raman spectra of these glasses and noted several bands that were assigned to the titanium-containing groups. Bobovich has also looked at the Raman spectra of titaniferous silicate glasses containing sodium. Very little investigation has been carried out with the infrared spectra of titania groups in vitreous silica. Tarte has observed the spectra of titanium groups in silicate glasses containing sodium and calcium. Manghani, Ferraro, and Basile have investigated Na2O-TiO2-SiO2 glasses by infrared spectroscopy. A major problem in the infrared investigation of these glasses is that the normal infrared spectra of the bulk silica matrix overshadows the spectra of the added components. This problem can be minimized by the use of a difference infrared (DIR) spectral technique that involves placing extremely thin plates of the titanium-containing vitreous silica and high purity silica in the sample and reference beams, respectively. In this note we will describe our technique for preparation of extremely thin glass plates (down to 8 μ thickness) and discuss the observed DIR bands for titanium-containing vitreous silica.