CHEMICAL BONDING AND STRUCTURE FIELD MAP OF M(3)X(4) COMPOUNDS WITH CLOSE PACKING OF ANIONS

A new classification of M(3)X(4) compounds with close packing of anion s relies on eight basic structure types differing in cation coordinati on number and/or stacking sequence. A unified technique is proposed fo r calculating the chemical-bonding factor K-b and the geometric factor s t(d) and b. The K-b-t(d) structure field map constructed in this way makes it possible to assess the critical values of K-b and t(d), whic h define the boundaries of structure fields. A procedure for calculati ng the changes in molar volume upon polymorphic transformations is dev eloped.