The present memory device (130) include first and second electrodes (132, 138), a passive layer (134) between the first and second electrodes (132, 138), and an active layer (136) between the first and second electrodes (132, 138) and into which ions from the passive layer (134) may be provided, and from which the ions may be provided into the passive layer (134). The active layer (136) is made up of a base material and an impurity therein. The combined the material and impurity have a lower diffusion coefficient than the base material alone.