The superionic conductivity of a variety of Li and Na solid electrolyte materials was therefore attributed to the concerted migration of charge carriers. For example, a significant degree of cooperative charge carrier motion characterized by low Haven ratios H r was identified in superionic conductors Li 10 GeP 2 S 12 (H r = 0.42) 40 and Na 10 GeP 2 S 12 (H r = 0.56). In a related study the superionic conductors Li novel superionic conductors. This was verified experimentally for a series of Li 6+x Sb 1-x S 5 I (M=Si, Ge, Sn) solid solutions in which partial substitution of Si 4+ in Sb 5+ sites and Li + in the lattice lead to the population of high-energy interstitial sites. The resulting disordered In this material, static vacancy configurations were found to enable 1D diffusion pathways leading to temporary occupation of nearest-neighbor Ca sites. In these Ca configurations, significant interactions of mobile ions resulted in the activation of a "vacancy-adjacent" concerted migration mechanism.