Goethite magnetic structure

The magnetic structure and hyperfme field of goethite (a-FeOOH). J. Phys. Cl 179-188... 

Like X-ray diffraction patterns, neutron and electron diffraction patterns provide averaged information about the structure of a compound. Details of these techniques are given in works by Hirsch et al. (1965) and West (1988). Neutron diffraction involves interaction of neutrons with the nuclei of the atoms. As the neutrons are scattered relatively evenly by all the atoms in the compound, they serve to indicate the positions of the protons in an oxide hydroxide. This technique has been applied to elucidation of the structure and/or magnetic properties of goethite (Szytula et al., 1968 Forsyth et al., 1968), akaganeite (Szytula et al., 1970), lepidocrocite (Oles et al., 1970 Christensen Norlund-Christensen, 1978), hematite (Samuelson Shirane, 1970 Fernet et al., 1984) and wiistite (Roth, 1960 Cheetham et al., 1971 Battle Cheetham, 1979). A neutron diffractogram of a 6-line ferrihydrite was recently produced by Jansen et al. (2002) and has helped to refine its structure (see chap. 2). 

Williams, R.J.P. (1988) The influence of silicate and phosphate on the structural and magnetic properties of synthetic goethite and related oxides. Clays Clay Min. 36 165-175... 

Due to the similar ionic radius (0.62 A [338]) and the existence of isostructural oxyhydroxide (GaOOH), Ga ions substituted Fe " " in the structure of goethite in a broad concentration range [300]. Ga-for-Fe substitution in the structure of goethite affects the reduction in HMF and Neel temperature due to magnetic dilution by nonmagnetic Ga " ions and to the formation of small Ga-goethite particles. 

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