Size dependence of the properties of hematite nanoparticles
Department of Physics, Building 307, Technical University of Denmark
DK-2800 Kgs. Lyngby, Denmark
Accepted: 21 August 2000
Samples of nanoparticles of hematite - with average size between 6 and 27 nm have been studied by use of Mössbauer spectroscopy. The superparamagnetic relaxation was analysed on the basis of the Néel-Brown expression for the relaxation time, . It was found that the value of increases with increasing particle volume, V, whereas the magnetic anisotropy energy constant, K, decreases. The electric quadrupole interaction, the isomer shift and the magnetic hyperfine field extrapolated to 0 K were found to be essentially independent of particle size.
PACS: 75.50.Tt – Fine-particle systems / 76.60.Es – Relaxation effects / 76.80.+y – Mössbauer effect; other γ-ray spectroscopy
© EDP Sciences, 2000