Fig. 1: Effect of K-doping on crystal phase of antiperovskite.

a Schematic diagram of cubic phase of antiperovskite stabilized by K-doping (Li in blue, O in red, H in yellow, Cl in green, K in purple). b PXRD patterns of orthorhombic Li2OHCl and cubic (Li2OH)1‒xKxCl at RT (~25 °C). c In situ PXRD patterns of Li2OHCl in the range between 30 and 100 °C. d In situ PXRD patterns of (Li2OH)0.99K0.01Cl in the range between 30 and 100 °C. e DSC curve of Li2OHCl. f DSC curve of (Li2OH)0.99K0.01Cl.