International Union of Crystallography, Acta Crystallographica Section B: Structural Science, 6(58), p. 948-964, 2002
DOI: 10.1107/s0108768102015070
Full text: Unavailable
A method is developed for the analysis and classification of orthosilicates and their analogs Mx (TO4) y containing M cations and tetrahedral TO4 anions. The method uses the concepts of coordination sequence and crystal structure `reduced' graphs and is optimized for orthostructures of any complexity. First, the suprapolyhedral level of crystal structure organization was studied, where T tetrahedra were considered as templates for condensing M polyhedra, constructing as a result T polyhedral microensembles. Using this methodology, the crystal structures of 54 orthosilicates and orthogermanates were analyzed within the first 12 coordination spheres of T nodes and were arranged into 21 topological types. The topological types were expanded with the analogs found within the orthostructures of phosphates, sulfates etc. T polyhedral microensembles were used for the topological classification of reconstruction mechanisms of thermal and baric phase transitions of orthosilicates.