The mixed alkali effect: Theoretical considerations

A cooperative theory for the composition dependence of activated processes in binary ionic oxide glasses (the mixed alkali effect) is proposed. It employs the regular solution model and introduces a molecular model, both of which are used in conjunction with appropriate spectroscopic data for obtaining an estimate of the magnitude of the theory's parameters. The nonlinear composition dependences of certain physical properties of mixed alkali systems, as well as their separation into exponential and pre-exponential factors, are shown to follow from these theoretical considerations.