Dislocations are fabricated into electrolyte membrane films to increase ion conductivity. Ion and/or electron irradiation causes the growth of vacancy clusters within the thin film and collapsing into Frank dislocation loops that exhibit high ion conductivity. Maximum ion conductivity is accomplished by spatially reorienting the Frank dislocation loops during a following heat-treatment of the membrane. Thereby the dislocation loops form surface-to-surface continuous dislocations along which ions may propagate between membrane surfaces with minimal activation energies. Dislocation densities in the range of 10.sup.8.about.10.sup.14 cm/cm.sup.3 may be fabricated with conventional irradiation techniques into ceramics such as, for example yttria stabilized zirconia and doped ceria.