Aluminate sodalites — A family with strained structures and ferroic phase transitions

The aluminate sodalites M ₈[Al₁₂O₂₄](XO ₄)₂, with M=Ca, Sr and X=S, Cr, Mo, W, are discussed in terms of their general structural characteristics. Special emphasis is given to the non-bonded O...O interactions between the cage anions and the sodalite framework, on one side, and to attractive cage anion — cage cation interactions, on the other side. Values for pseudocubic cell parameters, spontaneous deformation, superstructure multiplicities, transition temperatures and associated enthalpies, as well as symmetry information are given.