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Magnetocaloric effect and size‐dependent study of the magnetic properties of cobalt ferrite nanoparticles prepared by solvothermal synthesis
Author(s) -
VázquezVázquez C.,
Lovelle M.,
Mateo C.,
LópezQuintela M. A.,
BujánNúñez M. C.,
Serantes D.,
Baldomir D.,
Rivas J.
Publication year - 2008
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200778128
Subject(s) - superparamagnetism , materials science , crystallinity , particle size , nanoparticle , magnetic refrigeration , magnetization , cobalt , chemical engineering , cobalt ferrite , nanotechnology , analytical chemistry (journal) , chemistry , metallurgy , magnetic field , composite material , organic chemistry , physics , quantum mechanics , engineering
Cobalt ferrite (CoFe 2 O 4 ) nanoparticles from 2 nm to 15 nm were synthesized using a solvothermal procedure. In this non‐aqueous method, acetophenone was used as solvent and the particle size was controlled by changing the reaction temperature from 120 °C to 180 ºC. Nanoparticles show good crystallinity and uniformity above 140 °C, as determined by X‐ray diffraction and transmission electron microscopy. Magnetic measurements indicate superparamagnetic behaviour. Zero‐field‐cooling (ZFC) dc‐magnetisation experiments at 100 Oe show blocking temperatures ranging from 215 K to more than 305 K. Saturation magnetisation increases with particle size and a small decrease is observed when increasing the temperature. The magnetocaloric effect shown by these cobalt ferrite nanoparticles is reasonably high for nanomaterials. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)