Variations of Atomic Configurations in Stable Highly Symmetrical (Cubic) Structures

Abstract

The role of symmetry in the formation of stable crystal structures is considered on the examples of cubic (Fe,Ni)₈AgS₈ (\(Fm\bar 3m\)), KTb₃F₁₀ (\(Fm\bar 3m\)), (Ba,Pb)6(Cu,Fe,Ni)₂₅S₂₇ (\(Fm\bar 3m\)), and spinel Al₂MgO₄ (\(Fm\bar 3m\)). The variants of atomic arrangement in a standard lattice of symmetrically related sites that are often “uncomfortable” for the atoms falling into them, but satisfying a given stoichiometry are shown. The symmetry phenomenon significantly reducing the information space volume determining the structure is the main factor in crystal dynamics (order dynamics) in understanding the essence of crystallization processes.