Chapter 15: Fluorogermanate Glasses Check Access

Studies of binary fluorogermanate glasses are restricted to those containing NaF, KF, RbF, or PbF₂. Formation of these glasses requires great care during melting to prevent loss of fluorine. One study of lead fluorogermanate glasses, for example, was carried out on glasses which appear to have lost most, if not all, of the batched fluorine. In general, replacement of oxygen by fluorine reduces the density, refractive index, and glass transformation temperature, with little effect on the thermal expansion coefficient. The effect of fluorine on the electrical conductivity varies with the identity of the modifier ion in the glass. The properties of the alkali fluorogermanate glasses display the behavior typical of the germanate anomalies in those properties. Several studies of more complex fluorogermanate glasses indicate that fluorogermanate glasses can be readily formed over wide compositional ranges.