Colloque C 1, SupplCment au Journal de Physique I11 de mars 1997 Structural Analysis of Poor Crystalline Ferrite Precursor, y-FeOOH, Derived from Topotactic Hydrolysis of FeOCl

Abstract. Layered con~pound PcQC1 has iso-stnlctutre with y-FeOOH, which is considered as precursor of various magnetic materials in wet cl~emical sy~thesiis. y-FeOOH can be prepared by topotactic hydrolysis of FeOCl under a severe reaction condition (60°C, 2 weeks). But the samples are otten very poor in clystallinity under such a condition, so that the diffraction method can hardly be applicable. XAS spectroscopic studies at the Fe K-edge have been performed for FeOCl and its oxidehydroxide derivatives. By cotnparison of XANES spectra for between y-FeOOH and reference compounds such as FeOCI, FezOa, and Fe304, it is confinned that the iron octahedron becomes centrosymmetric as the chlorine atom was replaced with (OH-). Detailed stnlctore including bond angle as well as bond distlnce was obtained from Fe K-edge EXAFS analyses conibined with powder X-ray diffraction for y-PeOOH ovcr long range uy to-6 A which is very large value in case conventional EXAFS cuwe-fitting. 1