Structure and crystallization behaviour of Li2O-Fe2O3-SiO2 glasses

Iron-containing lithium disilicate glasses, other silicate and borate glasses, and crystallized lithium disilicate glasses have been studied by Raman spectroscopy, luminescence spectroscopy and X-ray diffraction. In the as-quenched glasses the presence of iron leads to a strong Raman band at 950 cm^–1 and to a broad Raman scattering continuum below 500cm^–1. There is also an emission due to trivalent iron at about 14000cm^–1 Lithium metasilicate has been identified in all crystallized glasses with more than 1% Fe₂O₃. It was possible to crystallize some of the glasses by irradiating them with intense blue laser light, and Raman spectra of various stages of photocrystallization have been obtained. By comparing the Raman spectra of the crystallized glasses with those of as-quenched glasses it is deduced that the trivalent iron has its own distinct local environment in the glass.