Structure cristalline d'une phase cubique desordonnee de type ReO3 excedentaire en anions : ZrF2,67O0,67

The crystal structure of cubic disordered anion-excess ReO₃-related ZrF_2.67O_0.67 (space group Pm3m, $\text{a}\text{= 3.997(2)}\text{A}\text{?}$) has been determined by single crystal X-ray diffraction techniques and refined to a R = 0.038-value. Two different kinds of anions are found, one X(1) slightly displaced (by 0.27 Å) from the ideal ReO₃-anionic site, the other X(2) more considerably (by 1.16 Å). As previously proposed (8,14) the anion-excess over the parent ReO₃-type structure, is accomodated by the formation of interstitial X(2)-X(2) pairs across a vacant X(1) site.The most likely anionic arrangements around zirconium atoms are assessed and on those basis, the structure is described as a disordered three-dimensional framework of edge sharing ZrX(1)₅X(2)₂ pentagonal bipyramids and corner sharing ZrX(1)₅X(2) distorted octahedra.