Fig. 1.

Phase diagram and structures of AMH. a Phase diagram of AMH. b Representation of the $Im\overline{3}m$ structure of the DMA phase VI²⁶. The oxygen and nitrogen atoms are represented with the blue and red spheres, respectively. The water and ammonia molecules occupy the same sites with a 50% probability. The white spheres show the 16 possible positions along the $⟨111⟩$ direction for the five hydrogen atoms in the unit cell. The other possible sites for H atoms along $⟨110⟩$ are less probable and not represented for clarity. c Representation of the predicted ionic P4/nmm structure according to ref. ³³. The same colour code is adopted for the atoms