Structures of Compounds with Diverse Bonds

The length of a given bond in a crystal structure depends on others ligands present. As shown in Table 5.13, a substitution in the AX polyhedron of a X ligand by another atom with lower EN increases d(A-X) of the remaining ligands, because of the increase of polarity of their bonds. 

Solid solutions are essentially more convenient materials for studying the mutual influence of atoms because of the possible monotonic change in composition with retention of the structure of a whole series of compounds [212], It is well-known that between the cell parameters of a mixed crystal and the concentration of the components there is a linear relation (Vegard s law). If the KBr—KI system, which gives a continuous series of solid solutions, is taken as an example, then the picture of gradual change in the K-X bond ionicity as the composition of the solution is 

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