Recombination structures, intergrowth structure series

A few considerations about possible schemes of relationships between inorganic crystal structures based on a systematic construction of complex structural types by means of a few operations (symmetry operations, topological transformations) applied to some building units (point systems, clusters, rods, sheets), have been previously reported in 3.9.1, following criteria suggested, for instance, by Hyde and Andersson (1989) and by Zvyagin (1993). 

It is interesting to observe that many real representatives of this series may be found in the Y-Co-Ga system. This is considered an example of the fact that, often, several members of a certain intergrowth series have representatives in the 

GROUP-SUBGROUP RELATIONS BETWEEN SPACE GROUPS FOR THE REPRESENTATION OF CRYSTAL-CHEMICAL RELATIONSHIPS 

The minimal steps of symmetry reduction can be classified according to the following terms  

Lattice equivalent ( translationengleich , abbreviation t). M contains all the translations of G, the crystal class of M is of lower symmetry than that of G. 

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Strictly related to this kind of description are the concepts of Recombination Structures and of Intergrowth Structure Series, to be discussed in the following see 3.9.4. 

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