Ionic compounds, such as alkali halides, exhibit a fixed stoichiometry and possess a broad band-gap, rendering thermally generated electrons or holes negligible. These materials represent the traditional group of ion conductors, where conductivity originates from the existence and movement of vacancies and/or self-interstitials. A well-known example is silver iodide, for which fast ionic conduction was reported in 1914. In an ionic crystal, there is a limitation on the type and quantity of defects that can arise, as they require an equal count of cation and anion atoms in their structure. Subsequently, only defect populations that maintain charge neutrality can emerge. Furthermore, there is no need to take into account the formation of antisite defects, given the substantial Coulomb energy required for an ion to be situated in the incorrect sublattice. Suppose the formation of vacancies and self-interstitials in the sublattice, arising from cations occupying cation sites. This particular disorder is referred to as Frenkel disorder.