(Na_0.38,Ca_0.31)MgFe₂P₃O₁₂

The structure of sodium calcium magnesium iron phosphate, (Na_0,38,Ca_0,31)MgFe₂P₃O₁₂, consists of an [MgFe₂(PO₄)₃]^- framework, built up by chains of edge-sharing (FeO₆-FeO₆-MgO₆) octahedra running along the [01] direction. The chains are linked together via the common corners of phosphate tetrahedra to form sheets parallel to the ab plane. Adjacent sheets are also connected through PO₄ tetrahedra, thus giving rise to an open framework with two different kinds of channels where the Na⁺ and Ca²⁺ cations are located.

Composé à charpente bidimensionnelle K₃Fe₃(AsO₄)₄

Tripotassium triiron(III) tetraarsenate, K₃Fe₃(AsO₄)₄, has been synthesized at high temperature by solid-state reaction. The structure is built up from corner- and edge-sharing between FeO₆ octahedra and AsO₄ tetrahedra. The structure can be described as infinite anionic layers parallel to the (010) plane. Alkali metal cations are located in the interlayer space. The relationship between the title compound and K₃Fe₃(PO₄)₄·H₂O structures is discussed. The title compound is isostructural with K₃Cr₃(AsO₄)₄.

Un nouveau diarséniate Cs₃Fe₂(AsO₄)₃ à environnement exclusivement pentagonal du fer

The crystal structure of the new iron(III) arsenate, viz. tricaesium diiron(III) tris(arsenate), Cs₃Fe₂(AsO₄)₃, is built up from corner-sharing AsO₄ tetrahedra and FeO₅ trigonal bipyramids forming a three-dimensional open framework, which contains two channels running along the c axis where the Cs⁺ cations are located. This compound is a rare example of an oxide possessing Fe exclusively in trigonal-bipyramidal coordination.

Sel mixte de lithium et de sodium eicosahydrate, Na_5.22Li_0.78[V₁₀O₂₈]·20H₂O

The structure of the title compound, sodium lithium decavanadate eicosahydrate, Na_5.22Li_0.78[V₁₀O₂₈]·20H₂O, is characterised by [V₁₀O₂₈]^6- polyanions which are linked by hydrogen bonds and Na⁺ ions. The centrosymmetric [V₁₀O₂₈]^6- polyanion consists of ten distorted VO₆ edge-sharing octahedra.