Brasil | Artículos de revistas
dc.creatorLima Junior, Enio
dc.creatorArelaro, Amanda Defendi
dc.creatorRechenberg, Hercilio Rodolfo
dc.creatorDuarte, Evandro Luiz
dc.creatorItri, Rosangela
dc.creatorCAVELIUS, C.
dc.creatorSHEN, H.
dc.creatorMATHUR, S.
dc.creatorGOYA, G. F.
dc.date.accessioned2012-10-20T04:00:32Z
dc.date.accessioned2018-07-04T15:39:13Z
dc.date.available2012-10-20T04:00:32Z
dc.date.available2018-07-04T15:39:13Z
dc.date.created2012-10-20T04:00:32Z
dc.date.issued2008
dc.identifierPHYSICA B-CONDENSED MATTER, v.403, n.23-24, p.4156-4159, 2008
dc.identifier0921-4526
dc.identifierhttp://producao.usp.br/handle/BDPI/29066
dc.identifier10.1016/j.physb.2008.08.018
dc.identifierhttp://dx.doi.org/10.1016/j.physb.2008.08.018
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1625708
dc.description.abstractWe investigate the formation of ferrihydrite nanoparticles (NPs) by hydrolysis of the Fe(III) alkoxide Fe(O(t)Bu)(3). Controlled amounts of water, up to 3.0 vol%, were added to the precursor solution yielding a series of hydrolyzed samples ranging from P0.0 (the unreacted precursor) to P3.0. X-ray diffraction (XRD) analysis evidenced the formation of high-crystalline ferrihydrite NP in sample P3.0, with grain size estimate of about 3.2 nm. The transition from the molecular precursor to the formation of crystalline magnetic NPs was followed through magnetization measurements M(T) and M(H), as well as Mossbauer spectroscopy (MS). M(T) measurements indicate a paramagnetic (PM) behavior for sample P0.0, characteristic of binuclear Fe-O-Fe units, which evolves to a superparamagnetic (SPM) behavior, with an energy barrier for the blocking process estimated for sample P3.0 as E(a) = 4.9 x 10(-21) J (E(a)/k(B) = 355 K), resulting in a high effective anisotropy constant K(eff) = 290 kJ/m(3). Magnetization loops at 5 K progressively change from PM-like to ferromagnetic-like shape upon increasing the hydrolysis process, although hysteresis (H(c) approximate to 500 Oe) only is apparent for P2.0 and higher. MS spectra at room temperature are PM/SPM doublets for all samples, while the MS spectra at T = 4.2 K reveal increasingly well-defined magnetic ordering as hydrolysis of the precursor stepwise progresses until well-crystallized ferrihydrite particles are formed. (C) 2008 Elsevier B.V. All rights reserved.
dc.languageeng
dc.publisherELSEVIER SCIENCE BV
dc.relationPhysica B-condensed Matter
dc.rightsCopyright ELSEVIER SCIENCE BV
dc.rightsrestrictedAccess
dc.subjectMagnetic nanoparticles
dc.subjectMossbauer spectroscopy
dc.subjectFerrihydrite
dc.titleMagnetic characterization of ferrihydrite nanoparticles synthesized by hydrolysis of Fe metal-organic precursor
dc.typeArtículos de revistas


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