Structure of glasses containing transition metal ions. Progress report, June 1, 1975--January 31, 1976. [Lead silicate and alkaline earth nitrate host glasses

Abstract

Summarized is work on the structure of transition metal ion-containing silicate, borate, and other insulator glasses. Raman spectra were measured on lead silicate and on alkali-alkaline earth nitrate glasses. Raman spectra of lead silicate glasses are strongly polarized. The high frequency modes are greatly broadened with respect to alkali silicate glasses and new features appear in the low frequency region related to the lead concentration. The nitrate glass Raman spectra show broadened bands in more or less the positions expected from the molecular modes of the nitrate ions. The broadening and some splitting of these bands can be interpreted in terms of a distribution of local fields around the nitrate ions. An extensive series of chromium-containing silicate and borate glasses were prepared. Chromium appears in both Cr/sup 3 +/ and Cr/sup 6 +/ states. The Raman spectra show that hexavalent chromium exists in the glasses as molecular chromate or dichromate-like clusters. Cr/sup 6 +/ is not incorporated into the network. The local environment of Cr/sup 3 +/ was investigated by optical absorption and luminescence spectroscopy. The optical properties of Cr/sup 3 +/ in silicates were largely independent of base glass composition, which is not true of the borates. A studymore » was begun on the local environment of iron in glasses through the optical absorption of Fe/sup 2 +/ and an observable red luminescence of Fe/sup 3 +/ which seems to be incorporated into the network. A characteristic yellow luminescence of very pure base glasses is also under investigation. 11 figures.« less