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  1. No Access

    Chapter and Conference Paper

    Disordered chromite in the Martian meteorite Allan Hills 84001

    At room temperature the 57Fe Mössbauer spectrum of chromite particles separated from the Martian meteorite Allan Hills 84001 is different from the Mössbauer spectrum of natural chromite. One hypothesis for this d...

    H. P. Gunnlaugsson, C. Bender Koch, K. Bharuth-Ram, M. Dietrich, Ö. Helgason… in ICAME 2007 (2009)

  2. No Access

    Chapter and Conference Paper

    Iron-57 Mössbauer spectroscopic study of fluorinated strontium orthoferrite

    The 57Fe Mössbauer spectra have been recorded at 300 K from an Fe4 + -containing oxygen-deficient perovskite-related SrFeO3 phase and its fluorinated derivative. The fluorinated phase shows complex magnetically s...

    F. J. Berry, E. A. Moore, X. Ren, Ö. Helgason, M. F. Thomas, S. Shim in ICAME 2007 (2009)

  3. No Access

    Chapter and Conference Paper

    Mössbauer spectroscopy of magnetic minerals in basalt on Earth and Mars

    Mössbauer spectroscopy of iron–titanium containing spinel phases is reviewed. New techniques are presented for determination of their composition using room-temperature Mössbauer spectroscopy. An example of th...

    H. P. Gunnlaugsson, H. Rasmussen, L. Kristjánsson, S. Steinthorsson… in ICAME 2007 (2009)

  4. No Access

    Article

    Disordered chromite in the Martian meteorite Allan Hills 84001

    At room temperature the 57Fe Mössbauer spectrum of chromite particles separated from the Martian meteorite Allan Hills 84001 is different from the Mössbauer spectrum of natural chromite. One hypothesis for this d...

    H. P. Gunnlaugsson, C. Bender Koch, K. Bharuth-Ram, M. Dietrich… in Hyperfine Interactions (2008)

  5. No Access

    Article

    Iron-57 Mössbauer spectroscopic study of fluorinated strontium orthoferrite

    The 57Fe Mössbauer spectra have been recorded at 300 K from an Fe4 + -containing oxygen-deficient perovskite-related SrFeO3 phase and its fluorinated derivative. The fluorinated phase shows complex magnetically s...

    F. J. Berry, E. A. Moore, X. Ren, Ö. Helgason, M. F. Thomas… in Hyperfine Interactions (2008)

  6. No Access

    Article

    Mössbauer spectroscopy of magnetic minerals in basalt on Earth and Mars

    Mössbauer spectroscopy of iron–titanium containing spinel phases is reviewed. New techniques are presented for determination of their composition using room-temperature Mössbauer spectroscopy. An example of th...

    H. P. Gunnlaugsson, H. Rasmussen, L. Kristjánsson… in Hyperfine Interactions (2008)

  7. No Access

    Chapter and Conference Paper

    Characterization of burned soil profiles by Mössbauer spectroscopy

    The characteristics of both natural burned and experimentally burned soil profiles as seen by Mössbauer spectroscopy are described. The results help in the identification of profiles where biological and/or ch...

    A. L. Vendelboe, H. P. Gunnlaugsson, Ö. Helgason, P. Nørnberg in ICAME 2005 (2007)

  8. No Access

    Article

    Characterization of burned soil profiles by Mössbauer spectroscopy

    The characteristics of both natural burned and experimentally burned soil profiles as seen by Mössbauer spectroscopy are described. The results help in the identification of profiles where biological and/or ch...

    A. L. Vendelboe, H. P. Gunnlaugsson, Ö. Helgason, P. Nørnberg in Hyperfine Interactions (2005)

  9. No Access

    Article

    Titanium-doped γ-Fe2O3: Reduction and oxidation properties

    Titanium-doped γ-Fe2O3 has been prepared by the calcination of a solid formed by the addition of aqueous ammonia to an aqueous solution of titanium- and iron-containing salts and boiling the precipitate under ref...

    I. Ayub, F. J. Berry, E. Crabb, Ö. Helgason in Journal of Materials Science (2004)

  10. No Access

    Chapter

    Nanocrystalline Oxides and Sulphides Prepared By Hydrothermal Processing and Mechanical Milling

    The synthesis of nanocrystalline tin-doped α-FeOOH (goethite) by hydrothermal processing of a precipitate and of nanocrystalline iron sulphides by mechanical milling gives particles which are well suited for e...

    F. J. Berry, A. Bohorquez, Ö. Helgason… in Material Research in Atomic Scale by Mössb… (2003)

  11. No Access

    Chapter

    The Kinetics of the Phase Transition in Ferrosilicon System

    Ferrosilicon is an important additive in steel production. The phase dynamics of the silicon rich part of the binary Fe-Si system has been the subject of particular controversy and there remains uncertainty ab...

    Ö. Helgason, B. Johannesson, B. Purser… in Mössbauer Spectroscopy in Materials Science (1999)

  12. No Access

    Chapter

    Structure and Properties of Tin-Doped Metal Oxides

    Tin-doped Fe3O4 prepared by solid state reactions is shown by X-ray powder diffraction and extended X-ray absorption fine structure to contain tin in the octahedral sites of the inverse spinel-related structure.

    F. J. Berry, C. Greaves, Ö. Helgason… in Mössbauer Spectroscopy in Materials Science (1999)

  13. No Access

    Article

    High temperature Mössbauer spectroscopy on the phase dynamics in ferrosilicon systems

    High temperature Mössbauer spectroscopy has been used for studying “in situ” the phase dynamics of the silicon rich part of the binary Fe-Si system. In particular the rate and mechanism of the transformation o...

    Ö. Helgason, Th. Magnusson, Th.I. Sigfusson in Hyperfine Interactions (1998)

  14. No Access

    Article

    Oxidation state of iron in mantle-derived magmas of the Icelandic rift zone

    Olivine tholeiites are mantle-derived magmas that are formed by partial melting of their deep sources and which have equilibrated with mineral assemblages at slightly different subcrustal pressure-temperature ...

    N. öskarsson, ö. Helgason, S. Steinthórsson in Hyperfine Interactions (1994)

  15. No Access

    Article

    Maghemite in basalt studied by Mössbauer spectroscopy in external magnetic field

    In the present study, we investigate the feasibility of detecting and determining the presence of maghemite in rock samples, by obtaining Mössbauer spectra in an external magnetic field of 1.6 T at room temper...

    ö. Helgason, H. P. Gunnlaugsson, S. Steinthorsson, C. Bender Koch… in Hyperfine Interactions (1994)

  16. No Access

    Article

    High temperature Mössbauer spectroscopy of titanomagnetite and maghemite in basalts

    Mössbauer spectroscopy of basalt lava samples, exhibiting reversible thermal magnetization (J s -T) curves with Curie temperatures of about 840 K, has revealed considerable amou...

    ö. Helgason, H. P. Gunnlaugsson, K. Jónsson, S. Steinthórsson in Hyperfine Interactions (1994)

  17. No Access

    Article

    Oxygen fugacity stratification of a magma chamber revealed by Mössbauer spectroscopy: evidence from the 1875 Askja eruption, N. Iceland

    Mössbauer spectra of volcanic glasses from the 1875 Askja eruption reveals that the dacitemagma chamber was stratified in oxygen fugacity. The eruption was triggered by basaltic magma which was intruded into t...

    Ö Helgason, N. Oskarsson, G. E. Sigvaldason in Hyperfine Interactions (1992)