Silica glass and melt

Silica glass or vitreous Si02 (abbreviated as v-SiOj) is a material of considerable mineralogical and technological importance. In many respects, it differs little from crystalline silica polymorphs such as quartz. For example, the enthalpy of melting of quartz is very low, and the uv absorption spectra of quartz and quartz glass are very similar (Phillip, 1971). X-ray studies (Mozzi and Warren, 1969 DaSilva et al., 1974 Coombs et al., 1985) indicate that the Si coordination number, average Si-O distance. 

Although the bulk of detailed work has been undertaken on v-SiOj, in situ x-ray studies of molten silicates at high temperature have confirmed that Si is coordinated to four oxygens in the molten as well as the glassy state (Waseda and Toguri, 1977, 1978) and yielded information on Si-0 bond lengths and some angular information (see Table 8.1). 

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