Structural characterization of strontium monoferrite SrFe2O4, a new stuffed framework compound

Single crystals of strontium monoferrite were obtained by growth from a mel t at 1550 degreesC. The monoclinic crystals belong to space group P112(1)/n (a = 8.1098(9), b = 9.1177(11), c = 10.8495(10) Angstrom, gamma = 91.53(1) degrees, V = 801.96(3) Angstrom (3), Z = 8, D-calc = 4.36 gcm(-3)). The str ucture was solved by direct methods using a single crystal diffraction data set. The main structural features of SrFe2O4 are layers, of FeO4-tetrahedr a perpendicular to the a axis. The stacking of the layers parallel to [100] results in a three-dimensional framework containing tunnels, where the str ontium cations are located. Individual layers can be described as being bui lt by the condensation of ditrigonally-shaped six-membered tetrahedral ring s. The sequence of up (U) and down (D) pointing apices within a single ring is UUUDDD. The structure belongs to the family of the zeolite ABW-type str uctures and is the first zeolite type compound with exclusively ferric iron occupying the tetrahedral positions of the framework. (C) 2001 Editions sc ientifiques ct medicales Elsevier SAS. All rights reserved.