Several of the characteristic properties of Li 3 OCl-a high degree of crystallographic ordering of mobile ions; low Schottky-pair formation energies, giving much higher concentrations of mobile vacancies than mobile interstitials; and higher mobilities for these interstitials than for corresponding vacancies-are shared by a number of other antiperovskite and structurally-related solid electrolytes . Understanding the effectiveness of different aliovalent doping schemes in Li 3 OCl is useful, therefore, not only because it may help direct the optimisation of ionic conductivity for this one material, but also because it can provide more general insights into doping responses for this entire class of solid electrolytes.