Cluster Self-Organization of Intermetallic Systems: Precursor Clusters K3, K5, and K6 for the Self-Assembly of Ba11Cd6Sb12-mS58 and Ba11Cd8Bi14-mS66 Crystal Structures
摘要
Using computer methods (ToposPro software package), a combinatorial–topological analysis and modeling of the self-assembly of Ba11Cd6Sb12-mS58 (a = 34.082 Å, b = 4.891 Å, c = 13.172 Å, β = 109.63°, V = 2068.20 Å3, C12/m1) and Ba11Cd8Bi14-mS66 (a = 28.193 Å, b = 4.893 Å, c = 16.823 Å, β = 90.84°, V = 2320.55 Å3, C12/m1) crystal structures are carried out. For Ba11Cd8Bi14-mS66, 116 cluster-structure variants are established: 2 variants with N = 3, 36 variants with N = 4, and 78 variants with N = 5. A variant of the self-assembly of the crystal structure is considered with the participation of clusters K3(8j) = 0@3 (BaCdBi) in the form of a ring of 3 atoms; K5(2a) = 0@5(BaCd2Bi2) in the form of two rings of three atoms with a common Ba atom; clusters K6(2c, 2/m) = 0@6(Ba4Bi2) in the form of paired tetrahedra; clusters K6(2c, 2/m) = 0@6(Ba2Cd2Bi2) in the form of paired tetrahedra; Bi atoms forming a chain; and Bi spacer atoms. For Ba11Cd6Sb12-mS58, 107 cluster-structure variants are established: 13 variants with N = 3, 39 variants with N = 4, 39 variants with N = 5, and 16 variants with N = 6. A variant of the self-assembly of a crystal structure with the participation of clusters K5(2a, 2/m) = 0@5(BaCd2Sb2) is considered in the form of two rings of three atoms with a common Ba atom; clusters K6(4e, –1) = 0@(Ba4Sb2) in the form of paired tetrahedra; clusters K6(4f, –1) = 0@(Ba2Cd2Sb2) in the form of paired tetrahedra; six atomic clusters K6(2c, 2/m) = 0@4(Ba4Sb2) in the form of paired tetrahedra; Cd and Sb atoms forming a chain; and Sb(4) spacer atoms. The symmetry and topological code of the self-assembly processes of 3D structures from precursor clusters are reconstructed in the following form: primary chain → layer → framework.