Chapter 8: RO Germanate Glasses Check Access

RO–GeO₂ glasses, where R is Ca, Sr, Ba, Cd, or Zn, all exhibit a large immiscibility region at low RO concentrations. Immiscibility has a strong influence on the properties of these glasses, resulting in two composition regions for property data, i.e. phase separated and homogeneous glasses. The refractive indices are only available for homogeneous glasses containing either SrO or BaO. Values of the densities and thermal expansion coefficients represent weighted averages of the values of the end member glasses for compositions within the immiscibility regions. The chemical durability and helium diffusivity have only been measured for phase separated samples. The glass transformation temperatures are dominated by the effects of phase separation. In those cases where data are available for homogeneous glasses, the germanate anomalies are present. Properties of ternary glasses in the soda lime germanate system have been studied in detail, while those for other soda-alkaline earth-germanate glasses are only available for a few glasses in each system. The usual germanate anomalies are found for the homogeneous soda lime germanate glasses.