0027392 - ÚACH 2006 RIV US eng J - Journal Article
Vejpravová, J. - Plocek, Jiří - Nižňanský, Daniel - Hutlová, Alžběta - Rehspringer, J.L. - Sechovský, V.
Magnetism of sol-gel fabricated CoFe2O4/SiO2 nanocomposites.
[Magnetické vlastnosti nanokompozitů CoFe2O4/SiO2 připravených metodou sol-gel.]
Journal of Applied Physics. Roč. 97, č. 12 (2005), 124304/1-124304/7. ISSN 0021-8979. E-ISSN 1089-7550
R&D Projects: GA AV ČR KJB4032402
Institutional research plan: CEZ:AV0Z40320502
Keywords : nanocrystalline iron particles * sol-gel method * ferrite nanoparticles
Subject RIV: CA - Inorganic Chemistry
Impact factor: 2.498, year: 2005

Details of synthesis and characterization of sol-gel-produced CoFe2O4 nanoparticles embedded in the amorphous SiO2 matrix are presented together with results of an extended magnetization study of these materials. The particle size was found to increase from 6 to 15 nm by varying the temperature of a subsequent annealing from 800 to 1100 degrees C. All samples exhibited superparamagnetic behavior with values of the blocking temperature T-B increasing with the particle size. At temperatures above T-B the magnetization curves follow the expected Langevin scaling of M vs H/T, which is consistent with the formation of the superparamagnetic state. For T < T-B, the coercivity field H-c was found to be proportional to root T and the frequency-dependent ac susceptibility was found to obey the Neel-Arrhenius law. Both observations are compatible with a model of noninteracting randomly oriented single-domain particles.

Syntéza, charakterizace a podobná magnetická studie nanočástic CoFe2O4 v amorfní matrici SiO2.
Permanent Link: http://hdl.handle.net/11104/0117496