  A new theoretical approach is presented for relating structural information
to transport properties in ion conducting network glasses. It relies on the
consideration of the different types of glass forming units and the charges
associated with them. Changes in the compositions of these units lead to a
re-distribution of Coulomb traps for the mobile ions and to a subsequent change
in long-range ionic mobilities. It is furthermore shown how measured changes of
the unit compositions can be explained by thermodynamic modeling. The theories
are tested against experiments on borophosphate glasses and yield good
agreement with the measured data both for the compositional changes of the
units and the variation of the activation energy.
