Systematics of fluorite-related structures. II. Structural diversity

The principles of systematics proposed in the previous paper are applied to the crystal structures with deficient fluorite-related frameworks. These f rameworks are classified into ones with face-sharing fluorite modules and o nes with quarter-of-face-sharing fluorite modules. It is shown that framewo rks with face-sharing modules may be described using the concept of supermo dule, i.e. set of modules from which the whole framework may be obtained by its periodic repetition. Example compounds are considered.