Basic structural types and polymorphisms in ABCl3 compounds

Thermodynamic study of CsCaCl3 using neutron diffraction

“…Of particular interest to this manuscript is the case where X represents a halide (F, Cl, Br, I), rather than oxygen. Ferna ´ndez et al 1 previously demonstrated that materials with the general formula ABCl 3 crystallise in this perovskite structure, with a tolerance factor between 0.81 and 0.9. 2,3 Halide-based perovskites, as with the oxide analogues, often demonstrate temperature and pressure-driven polymorphism, with crystallographic symmetry deviating from or converging towards the cubic aristotype via octahedral rotation/distortion, or A-site cation displacement.…”

“…For example, cubic CsSrCl 3 transforms to tetragonal then orthorhombic then monoclinic symmetry at 385 K, 375 K and 362 K respectively. 1,4 CsPbCl 3 is also highly polymorphic, with multiple phase transitions over a very narrow temperature range. 5 The application of hydrostatic pressure as a tuning parameter is an efficient way of generating materials with new crystalline structures with intrinsic physical properties.…”