Hiromi MAEZAKI

Viscosity of Mixed Alkali Glasses far below Glass Transition Temperature

Kazumasa MATUSITA

It is known that the thermal stability of glasses, such as high precise new glass and high-level radioactive-waste glasses, is closely related to viscosity.
The electrical conductivities of the glasses containing two kinds of alkali ion decrease by about 5-order of magnitude compared with single alkali glasses, this phenomenon is called the mixed alkali effect.
In this study, the viscosity of the mixed alkali glass far below glass transition temperature (Tg) was measured by the fiber bending method.
As a result, it was observed that viscosity change with composition is almost same above and below the glass transition temperature.
And it was confirmed that viscosity of mixed alkali glasses was lower than single alkali glasses about one-order of magnitude.
It is ascertained that viscosity does not show remarkable mixed alkali effect, such as electrical conductivity.
It is concluded that the thermal stability of glasses are not affected by the mixed ratio of two alkali oxides.