Rodalquilarite revisited: The hydrothermal synthesis and structural reinvestigation of H3Fe2(TeO3)(4)Cl

The known mineral rodalquilarite, H3Fe2(TeO3)(4)Cl, was obtained as high qu ality single crystals via hydrothermal reactions. This material crystallize s in the triclinic space group, PT, with cell constants of a = 5.103(2) Ang strom, b = 6.653(2) Angstrom, c = 9.012(3) Angstrom, alpha = 73.40(2)degree s, beta = 78.03(2), gamma = 76.76(2), V= 282.1(2) Angstrom(3) and was obtai ned from an NH4Cl solution that was heated at 375 degrees C for 3 days, A d etailed structural characterization was performed (R = 0.039, R-w = 0.050) and showed that this material is based on layers consisting of edge-sharing FeO6 octahedra which are interconnected by TeO3 pyramids which are complet ed by the presence of a terminal hydrogen atom. Additionally, a second set of TeO3 pyramids attached to the FeO6 octahedra are linked across the layer s by a shared hydrogen atom. The layers are held together only through thes e O-H-O interactions and additional weak Te-CI interactions. In this study, we compare this structure to a previous report of rodalquila rite and a reported triclinic form of Fe2Te4O11, which may have been miside ntified and is also the title compound. In addition, we have obtained the b and gap of this material by diffuse reflectance spectroscopy and find it to be a wide band gap (E-g = 2.51 eV) material. The DC magnetic susceptibilit y was also obtained and showed that the title compound is antiferromagnetic with a T-N Of 29 K, (C) 1999 Academic Press.