Conductivity Activation Energy Relations in High‐Sodium‐Content Borate and Aluminoborate Glasses

Glasses were prepared having compositions x Na 2 O + (1 − x )B 2 O 3 and x Na 2 O + (1 − x )( n B 2 O 3 ·Al 2 O 3 ) where n = 4.0 and 6.7, and their conductivities and activation energies were determined up to 70 mol% Na 2 O. Below 50 mol% Na 2 O, the conductivity activation energy decreases with Na 2 O content, which is attributed to a decreasing cation jump distance. Above 50 mol% Na 2 O, however, the activation energy increases with Na 2 O content. These measurements are the first to clearly show a conductivity activation energy increasing with alkali oxide content, an effect which is not yet explained by any of the current models of ionic conduction in glass.