Impact of silica environment on hyperfine interactions in ε-Fe.sub.2./sub.O.sub.3./sub. nanoparticles

0469997 - FZÚ 2017 RIV NL eng J - Journal Article
Kubíčková, L. - Kohout, J. - Brázda, Petr - Veverka, Miroslav - Kmječ, T. - Kubániová, D. - Bezdička, Petr - Klementová, Mariana - Šantavá, Eva - Závěta, Karel
Impact of silica environment on hyperfine interactions in ε-Fe₂O₃ nanoparticles.
Hyperfine Interactions. Roč. 231, č. 1 (2016), s. 1-10, č. článku 159. ISSN 0304-3843
Institutional support: RVO:68378271 ; RVO:61388980
Keywords : iron oxide * polymorph of ferric oxide * ⁵⁷Fe Mössbauer spectrometry * ferrimagnetic nanoparticles * giant coercive field * spin-reorientation transition
OECD category: Condensed matter physics (including formerly solid state physics, supercond.); Inorganic and nuclear chemistry (UACH-T)

Magnetic nanoparticles have found broad applications in medicine, especially for cell targeting and transport, and as contrast agents in MRI. Our samples of eε-Fe2O3 nanoparticles were prepared by annealing in silica matrix, which was leached off and the bare particles were then coated with amorphous silica layers of various thicknesses. The distribution of particle sizes was determined from the TEM pictures giving the average size ∼20 nm and the thickness of silica coating ∼5; 8; 12; 19 nm. The particles were further characterized by the XRPD and DC magnetic measurements. The nanoparticles co nsisted mainly of ε-Fe2O3 with admixtures of ∼1% of the α phase and less than 1 % of the γ phase. The hysteresis loops displayed coercivities of ∼2 T at room temperature. The parameters of hyperfine interactions were derived from transmission Mössbauer spectra.

Permanent Link: http://hdl.handle.net/11104/0267742