Hypothetical AlF3 crystal structures

Applying a structure prediction computer programme (GRINSP=Geometrically Restrained INorganic Structure Prediction), the occurrence of 6-connected 3D networks was investigated, through AlF6 octahedra exclusive corner sharing. The five known AlF3 varieties were reproduced (α-, β-, η-, κ- and τ-AlF3) and seven hypothetical models were predicted. Among these still to be synthesized AlF3 phases, one can recognize two known structure types (TlCa2Ta5O15, Ba4CoTa10O30) and some easy to imagine intergrowths; however, a few others are completely unexpected, though simple. A comparison of the ab initio total energies of all the structures is provided, leading to the conclusion that the virtual models could well be viable.

Hypothetical AlF3 structure with a dense packing of corner-sharing AlF6 octahedra packed in tetrahedral blocks.Figure optionsDownload as PowerPoint slide