Perovskite Distortion Inverted: Crystal Structures of (A 3 N)As (A = Mg, Ca, Sr, Ba)

PolyDis: simple quantification tool for distortion of polyhedra in crystalline solids

A new simple approach to quantitative measures of coordination polyhedra distortions from ideal symmetry is provided with PolyDis. Within the mathematical basis, it minimizes the normalized displacements of given polyhedra to the ideal shape. Applications are discussed, where PolyDis was used to analyze the temperature dependent distortion of LaAlO3, rare earth metal radius dependent distortion of RMnO3 and the increasing structural distortion of (A 3N)As with varying alkaline earth metal, all being perovskites. Additionally, the more complex structures of SrCuRSe3 and CsCu3 R 2Se5 comprising trigonal prisms, octahedra and tetrahedra are treated with PolyDis.