Isomorphous Series in Crystals of MeSO₄.nH₂O Type

Abstract

Historically, the scope of the term isomorphism has been extended several times so that the meaning imparted by the various authors to it is not always the same. For this reason it is necessary to specify what is meant by the term when using it. For example, when isovalent isomorphism is discussed, cases in which the ion-for-ion substitution leads to changes in the symmetry of ligand field are also included (Vinokurov). Obviously, the two compounds participating in the process must have different structures, i.e. this is a case of the so-called forced isomorphism or isodimorphism. Although isodimorphism phenomena show great variety, in all of them a discontinuity in the series of mixed crystals must occur. Most often a single discontinuity is observed. Thus, two isomorphous series of mixed crystals occur in the system, each of which has the crystal structure of the respective end member — pure salt.