K1+2xNi1-xFe2(AsO4)3 (x = 0,125): un nouvel arséniate à structure de type α-CrPO4.

A new arsenate K_1+2xNi_1-xFe₂(AsO₄)3 (x = 1/8) {potassium nickel diiron(III) tris[arsenate(V)]} was synthesized using a flux method and its crystal structure was determined from single-crystal X-ray diffraction data. This material was also characterized by qualitative energy dispersive X-ray spectroscopy (EDS) analysis. The crystal structure belongs to the α-CrPO₄-structure type, space group Imma. It consists of a three-dimensional-framework built up from FeO₆ and Ni_0.875□_1.25O₆-octahedra and AsO₄-tetrahedra that are sharing corners and/or edges, generating tunnels running along the [010] and [001] directions in which the potassium cations are located. The proposed structural model was validated by bond-valence-sum calculations, charge-distribution (CHARDI) and Madelung energy analyses. [ABSTRACT FROM AUTHOR]