J. Phys. IV France 07 (1997) C1-335-C1-336
Structural Analysis of Poor Crystalline Ferrite Precursor, γ-FeOOH, Derived from Topotactic Hydrolysis of FeOClJ.-H. Choy1, J.-B. Yoon1 and K.-S. Han2
1 Center for Molecular Catalysis, Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-742, Korea
2 Inorganic Chemistry Division, National Institute of Technology and Quality, Kyunggi-do 427-010, Korea
Layered compound FeOC1 has iso-stucture with γ-FeOOH, which is considered as precursor of various magnetic materials in wet chemical synthesis. γ-FeOOHcan be prepared by topotactic hydrolysis of FeOCl under a severe reaction condition (60°C, 2 weeks). But the samples are often very poor in crystallinity 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 oxide/hydroxide derivatives. By comparison of XANES spectra for between γ-FeOOH and reference compounds such as FeOCl, Fe2O3, and Fe3O4, it is confirmed that the iron octahedron becomes centrosymmetric as the chlorine atom was replaced with (OH). Detailed structure including bond angle as well as bond distance was obtained from Fe K-edge EXAFS analyses combined with powder X-ray diffraction for γ-FeOOH over long range up to 6 Å which is very large value in case conventional EXAFS curve-fitting.
© EDP Sciences 1997