Modeling of self-organization processes in crystal-forming systems. Structural mechanism of self-assembly of zirconosilicate Na2ZrSi2O7 from suprapolyhedral clusters

Topological analysis of the crystal structure of Na₂ZrSi₂O₇ (parakeldyshite, space group P1^–) with an MT framework, where M are ZrO₆ octahedra and T are SiO₄ tetrahedra, was carried out by the method of coordination sequences (TOPOS.3.2 program package), and the self-organization of this structure was modeled. The cyclic-type suprapolyhedral cluster precursor Na₂M₂T₄ with the local symmetry 1^– was identified by bicolor decomposition of the 4646+664 net. The cluster is composed of six polyhedra with two Na atoms located in the center. The precursors control the evolution of high-level crystal-forming clusters. The cluster coordination number is six. The centers of eight cluster precursors in the superprecursor of the Na₂ZrSi₂O₇ structure are related by translation vectors.