| Issue |
Europhys. Lett.
Volume 52, Number 2, October II 2000
|
|
|---|---|---|
| Page(s) | 217 - 223 | |
| Section | Condensed matter: electronic structure, electrical, magnetic, and optical properties | |
| DOI | https://doi.org/10.1209/epl/i2000-00426-2 | |
| Published online | 01 September 2002 | |
Size dependence of the properties of hematite nanoparticles
Department of Physics, Building 307, Technical University of Denmark
DK-2800 Kgs. Lyngby, Denmark
Received:
10
July
2000
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, ![$\tau = \tau_0 \exp[KV/kT]$](/articles/epl/abs/2000/20/6263/6263_tex_eq3.png)
. 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
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