Cluster self-organization of inorganic crystal-forming systems: Templated nanocluster precursors and self-assembly of framework MT structures of A/B,Zr silicates ( A = Na, K; B = Ca, Sr).

Ilyushin, G.

The basic concepts that are used to describe crystallization as a phenomenon of the hierarchical (cluster) self-organization of a chemical system are considered. The templation of theoretically possible nan-ocluster precursors composed of M octahedra and T tetrahedra by atoms of ( A) alkaline and ( B) alkaline earth metals is considered for the first time. A relationship between the A/B,M,T composition of templated nanocluster precursors with the composition of A/B,M silicates is established. The model that is developed is used to search for nanocluster precursors in framework MT structures of A/B,Zr silicates. Computer methods (TOPOS 4.0 program package) were used to perform complete 3 D reconstruction of the self-assembly of all (four) structural types of A/B,Zr silicates ( A = Na, K; B = Ca, Sr) with frameworks of the MTO type: nan-ocluster precursor S-primary chain S-microlayer S-microframework S. The invariant type of mono-cyclic nanocluster precursor M T (with the point symmetries $\bar 1$ and 2), stabilized by one or two template cations ( A and B), is determined. Bifurcations of the paths of evolution at the S level (structural branching point) are established for the self-assembly of the following frameworks: MT-1 in CaZrSiO (gittinsite, C2), MT-2 in SrZrSiO ( P2/ c); MT-3 in NaZrSiO (parakeldyshite,), KZrSiO (khibinskite, P2/ b), and KZrGeO ( C2/ c); and MT-4 in NaZrSiO (HO)( C2/ c), NaScSiO ( Pbnm), and KScSiO ( P6/ mmc).

MOLECULAR self-assembly; CRYSTALLIZATION; CRYSTAL structure; SILICATES; CLUSTER analysis (Statistics); BIFURCATION theory; IMAGE reconstruction

Crystallography Reports, 2012, Vol 57, Issue 2, p169

1063-7745

Academic Journal

10.1134/S1063774512020095