Complete structure and cation orientation in the perovskite photovoltaic methylammonium lead iodide between 100 and 352 K

The methylammonium cation in CH3NH3PbI3 demonstrates increasing positional disorder on heating from 100 K to 352 K. In the tetragonal phase, stable between 165 K and 327 K, the cation is disordered over four sites directed toward the faces of the distorted cubic PbI3(-) framework and migrates towards the cavity centre with increasing temperature.