Viscosity and configuration entropy of glasses for CHROMPIC vitrification

The composition and temperature dependence of viscosity and configuration entropy of glasses with chemical composition close to that used for CHROMPIC radioactive waste vitrification were studied. The composition of fifteen studied glasses was derived from the composition of currently used glass frit by increasing/decreasing the content of each particular oxide and retaining the same relative amounts of the other components. The high-temperature viscosity in the range (101.8–103.0) dPa s was measured by the falling ball method while the low-temperature viscosity in the range (108–1012) dPa s was measured by the thermomechanical analysis. The experimental viscosity data were smoothed by the Vogel–Fulcher–Tammann viscosity equation. The temperature–composition dependence of viscosity was described by the Adam and Gibbs viscosity equation. The influence of increasing/decreasing content of particular oxides on the values of parameters of the Adam and Gibbs viscosity equation and on the value of configuration entropy was quantified and discussed.