The Layered Structures of Ternary Chalcogenides with Alkali and Transition Metals

Abstract

The structure of binary fluorides and oxides with alkali and alkaline-earth metals can be largely understood by means of the supposition of electrostatic binding forces. Thus the sequence of structure types with changing co-ordination numbers for cations and anions depending on their radial quotients, can be nearly quantitatively predicted by a simple model using electrostatically attracting and repelling forces. Moreover, the lattice energies calculated by means of the electrostatic model agree satisfactorily with those which can be experimentally determined by means of the Born-Haber cycle. The dominant role of the electrostatic binding forces decreases considerably if one changes over to the fluorides and oxides of the remaining main group and transition metals, especially when the electropositive atoms are in higher oxidation states.