Goethite magnetic properties

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... 

Bocqnet S (1996) Snperparamagnetism and the Mossbaner spectrum of goethite a comment on a recent proposal by Coey et al. J Phys Condensed Matter 8 111-113 Bodker F, Hansen MF, Bender Koch C, Lefmann K, Morap S (2000) Magnetic properties of hematite nanoparticles. Phys Rev B 61 6826-6838... 

Quin TG, Long GL, Benson CG, Mann S, Williams RJP (1988) Influenoe of silieon and phosphorus on stractmal and magnetic properties of synthetie goethite and related oxides. Clays Clay Minerals... 

The goethite consists of fairly monodisperse acicular crystals about 20-25 nm long, 10-15 nm wide and 4 10 nm thick (Fig. 5-4 bottom, left). The diamond-shaped cross section indicates that the crystals are again essentially bounded by 101 faces. The surface area is ca. 130 m /g and the magnetic hyperfine field at RT is 38-39 T (for further properties... 

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