Binary and pseudobinary compounds AB like NaCl and CaCO₃, with the center of charge at carbon position, are characterized by self-coordination numbers of nearest, second and third neighbors T₁ T₂ T₃ of A and B positions. The maximum Madelung factor of compounds with identical T_i values of A and B atoms is obtained for a maximum of B positions at the border of the A–A Dirichlet domain. The A and B positions form a packing with different T_i values, if all B positions are on the border of the Dirichlet domain. This packing like the primitive cubic packing of Na and Cl atoms with Ti values 6 12 8 or the rhombohedrally distorted packing 6 8 6 of CaCO₃ as morphological lattice complexes can be related to cubic NaCl crystals or the cleaved rhombohedron of calcite. A different habit of crystals is expected for sphere, rod or layered packings. Many well-defined nanoparticles can be obtained from microemulsions at variation of temperature, water content or water partial pressure.

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