Further studies on the IR spectra of silicate glasses

Infrared spectra of the PbOSiO2 glass system were studied by the KBr method. The absorption peaks show some different features as compared with the author's previous work on infrared spectra of alkali silicate glasses. It was found that with increasing PbO content the main absorption peak at a wave number larger than 1000 cm−1 originally shifts to less than 1000 cm−1 as the PbO content reaches 40 mol%; at the same composition occurs the abrupt change in property-composition curves of the PbOSiO2 glass system. It is interesting that the absorption peak of non-bridging SiO links near 950 cm−1, being typical in the IR spectra of Na2O·2SiO2 glass, is rather weak in the spectra of Li2O·2SiO2 glass and almost disappears in that of PbO·2SiO2 glass; this agrees with the different stability of the crystalline phase of corresponding bisilicate compounds. Infrared spectra of a series of Na2OCaOSiO2 glasses have also been studied. A new peak appears when the SiO2 content is below 74 mol% and the glass composition enters the narrow region of commercial soda-lime glasses. As to K2OPbOSiO2 glasses, the shifting of the main absorption peak becomes obvious when the glass composition is near those of commercial glasses. Discussions have been given on different structural groups of SiO links adjacent with different metal ions. An attempt has been made to give some structural interpretations of the reason why the chemical compositions of commercial soda-lime and potash-lead silicate glasses are concentrated in a narrow region.