Space-group multiplicities of polymorphs of inorganic compounds and lattice enthalpies

Abstract

The relationships between lattice enthalpies (LEs) and multiplicities of points in general positions or orders of the point groups of the space groups have been studied for 71 inorganic compounds exhibiting at least two polymorphs. The LEs of the ionic crystals have been obtained through the Born–Haber (BH) thermochemical cycle, including halides, chalcogenides, oxohalides, and binary and complex oxides. It has been found for the range of LEs (600–39,000 kJ mol−1) and relevant crystal structures that: (i) most of the polymorphs with higher multiplicities correspond to those stable under standard conditions compared to the lower-in-stability polymorphs and (ii) the products of multiplicity times order depend hyperbolically on the LE per unit symmetry point in general position.