Thermal conductivities of the M2O-SiO2 (M=Li, Na and K) systems have been measured over a wide temperature range between room temperature and 1573 K using the nonstationary hot wire method to investigate the effect of the ionicity of nonbridging oxygen ions on the thermal conductivities of molten alkali silicates. The thermal conductivities for (mol%) 33Li2O.67SiO2, 33Na2O.67SiO2 and 33K2O.67SiO2 were recorded as 1.05, 0.73 and 0.55 WlmK at the respective melting points. It has been found from the ion refractivity of oxygen that silicates containing more ionic nonbridging oxygen ions have smaller thermal conductivities. An identical linear relation has been obtained between the logarithm of viscosity and the thermal conductivity of molten silicates regardless of basic oxides. This also indicates that the thermal conductivities of molten silicates are affected by the ionic character of chemical bonds between cations of basic oxides and nonbridging oxygen ions.
|Number of pages||6|
|Journal||Physics and Chemistry of Glasses|
|Publication status||Published - 2001 Feb 1|
ASJC Scopus subject areas
- Ceramics and Composites
- Physical and Theoretical Chemistry