Modular aspects of crystal structures

STRUCTURE FAMILIES RECOMBINATION STRUCTURES , MODULAR ASPECTS OF CRYSTAL STRUCTURES 

Tantum elementa queunt permutato ordine solo, T. Lucreti Cari Liber primus De Rerum Natura, 827 

Emphasis to a similar approach has been given by Zvyagin (1993). He pointed out that many crystal structures can be represented as a composite of certain standard construction modules and various combinations, distributions and arrangements of these. The simplest example of a modular structure is the densest packing 

Principles and types of modular series have been summarized in a book by Ferraris et al. (2004). A hierarchical classification of structure has been introduced as well as the application of modularity to structure description and modelling. The order/disorder theory has been presented as fundamental to developing a systematic theory of polytypism, dealing with structures based on both ordered and disordered stacking of one or more layers. The structures of a great number of compounds (minerals, complex oxides, salts, etc.) have been described and discussed. 

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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