Der Übergang von isolierten dimeren [AlF4/1F2/2]2 Gruppen aus kantenverknüpften Oktaedern zu unendlichen linearen ${_{\infty}^1}$[AlF4/1F2/2]‐Ketten eckenverknüpfter Oktaeder in den tetragonalen Verbindungen (Sr,M)AlF5 (M = Ca,Ba) — der Einfluß des unterschiedlichen Substitutionsgrades von Sr durch Ba und Ca

The Transition from Isolated Dimeric AlF_4/1F_2/2]₂ Groups of Edge‐sharing Octahedra to Infinitive Linear Chains AlF_4/1F_2/2] of Corner‐sharing Octahedra within the Tetragonal Compounds (Sr, M)AlF₅ (M = Ca, Ba) — the Influence of the Different Substituition Rate of Sr by Ba and Ca The solid solutions Sr_0.87(1)Ba_0.13(1)AlF₅, Sr_0.75(1)Ba_0.25(1)AlF₅, Sr_0.24(1)Ba_0.76(1)AlF₅ and Ca_0.13(3)Sr_0.56(6)Ba_0.31(3)AlF₅ have been prepared by solid state reactions from the binary fluorides. The crystal structures have been determined by means of single crystal diffraction data. All compounds crystallize tetragonal body‐centered in different structure types which are composed of two main structural building blocks. The first building block is common to all solid solutions and consists of linear chains of trans corner‐sharing AlF₆] octahedra propagating along the c axis. Two opposite equatorial fluorine atoms of this chain have been replaced by other AlF₆] octahedra thus forming branching chains which give rise to a tunnel arrangement. The alkaline earth metal atoms are located inside the tunnels and those structural motifs extend parallel the tunnel axis which lead to the formation of the different structure types. By increasing the Ba content of the solid solutions a transition from isolated dimeric groups AlF_4/1F_2/2]₂ of edge‐sharing octahedra, and by additional incorporation of Ca from disordered zigzag chains, to linear infinitive AlF_4/1F_2/2] chains of corner‐sharing octahedra has been established.