The initial stages of formation of precursor clusters are considered in an evolving system containing various types of polyhedra:
T tetrahedra and M polyhedra (pyramids, octahedra, and others). A graph topological representation of the precursor clusters
of different self-organization levels of a chemical system is given. The model has been applied to find precursor clusters
for Na,Ti-silicates that crystallize in the Na-Ti-Si-O(H) systems. For ramzaite Na
2Ti
2Si
2O
9 (RAM) and a dimorph of natisite (NAT), namely, paranatisite Na
2TiSiO
5 (PNAT), computer techniques (the TOPOS 4.0 program package) have been used to perform the full 3D reconstruction of structure
self-assembly: precursor cluster-primary chain-microlayer-microframework (supraprecursor). New types of eight-polyhedral ring
precursor clusters have been identified. The packing specifics of precursor clusters in crystal-forming microlayers determine
the platy habit of Na,Ti-silicate single crystals.
Original Russian Text © G.D. Ilyushin, 2006, published in Zhurnal Neorganicheskoi Khimii, 2006, Vol. 51, No. 11, pp. 1894–1905.