Journal
CERAMICS INTERNATIONAL
Volume 39, Issue 5, Pages 5651-5658Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2012.12.081
Keywords
Sol-gel; Superparamagnetism; MnFe2O4; Magnetic nanomaterials
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Funding
- Fatih University under BAP [P50021104-B]
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A polyvinylpyrrolidone (PVP)/MnFe2O4 nanocomposite was prepared by the sol-gel autocombustion method and its structural, thermal, spectroscoppic, morphological and magnetic characterizations were done by XRD, FT-IR, TGA, SEM and VSM techniques. The presence of MnFe2O4 was confirmed by XRD and the size of crystallites was estimated to be 11 +/- 3 nm. Morphology analysis by SEM revealed spherical agglomerates of 15 nm. The magnetization curves confirm a superparamagnetic behavior with a blocking temperature of 287 K. The M-r/M-s value suggests the presence of uniaxial anisotropy in MnFe2O4 nanoparticles, instead of the expected cubic anisotropy according to the Stoner-Wohlfarth model. The effective magnetic anisotropy constant K-eff has been determined to be about 1.42 x 10(6) erg/cm(3) which is significantly higher than that of the bulk MnFe2O4. This suggests a strong magnetic coupling between magnetically ordered core spins and disordered surface spins of the nanoparticles in the nanocomposite. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
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