Oleate-based hydrothermal preparation of CoFe.sub.2./sub.O.sub.4./sub. nanoparticles, and their magnetic properties with respect to particle size and surface coating

0448155 - FZÚ 2016 RIV NL eng J - Journal Article
Repko, A. - Vejpravová, Jana - Vacková, Taťana - Zákutná, D. - Nižňanský, D.
Oleate-based hydrothermal preparation of CoFe₂O₄ nanoparticles, and their magnetic properties with respect to particle size and surface coating.
Journal of Magnetism and Magnetic Materials. Roč. 390, Sep (2015), s. 142-151. ISSN 0304-8853. E-ISSN 1873-4766
R&D Projects: GA TA ČR(CZ) TE01020118
Institutional support: RVO:68378271 ; RVO:61389013
Keywords : superparamagnetism * size effect * monodisperse nanocrystals * hydrothermal synthesis * cobalt iron oxide * titania
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 2.357, year: 2015

hydrolysis of Co-Fe oleate in the presence of pentanol/octanol/toluene and water. The particle size (6 – 10 nm) was controlled by the composition of the organic solvent and temperature. Magnetic properties were then investigated with respect to the particle size and surface modification with citric acid or titanium dioxide. The as-prepared hydrophobic nanoparticles (coated by oleic acid) had a minimum inter-particle distance of 2.5 nm. Their apparent blocking temperature was 180 K, 280 K and 330 K for the particles with size of 6, 9 or 10.5 nm,respectively. Replacement of oleic acid on the surface by citric acid decreased inter-particle distance to less than 1 nm, and increased blocking temperature by ca. 10 K. Coating with titanium dioxide, supported by nitrilotri(methylphosphonic acid), caused increase of the particle spacing, and lowering of the blocking temperature by ca. 20 K.
Permanent Link: http://hdl.handle.net/11104/0249876