A Study of Na 2 O-TiO 2 -SiO 2 Glasses by Infrared Spectroscopy

The infrared absorption spectra of six Na 2 O-TiO 2 -SiO 2 glasses in the frequency range of 1600 to 200 cm −1 are reported. These glasses, having a SiO 2 /Na 2 O molar ratio of 1.07 to 3.54, and containing 20 or 25 mole % TiO 2 , demonstrate two main absorptions at ∼950 cm −1 and at ∼450 cm −1 . A weak absorption at ∼790 cm −1 becomes progressively weaker in intensity, and a weak shoulder at 1050 cm −1 appears with increasing Na 2 O content. The frequency of the absorption band at ∼950 cm −1 is found to decrease markedly and systematically with a decrease in the SiO 2 /Na 2 O molar ratio, whereas the frequency of the band at ∼450cm −1 shows a slight increase. The infrared results may be interpreted in terms of a lowering of symmetry occurring for the SiO 4 units. The effect of TiO 2 content on the relationship between vibrational frequency is discussed. The frequency composition curves for glasses containing 20 and 25 mole % of TiO 2 intersect at SiO 2 /Na 2 O ratio ∼2. A reversal in the frequency vs SiO 2 /Na 2 O ratio relation was also found at SiO 2 /Na 2 O ∼2 for the sodium silicate glasses.