Fig. 6: Crystal structure of MAPbI3 in the orthorhombic phase.
From: Incipient ferroelectricity in methylammonium lead halide perovskites
The structure (with the space group Pnma and tilt system a-b+a-) viewed in a a-b plane and b a–c plane. PbI6 octahedra are highlighted in purple. c Hydrogen bonds (indicated by dotted lines) between three H atoms in the NH3 group and one axial I [IA(1)] atom and two equatorial I [IE(2) and IE(2’)] atoms. Reproduced from ref. 59 with permission from the Royal Society of Chemistry.
