Structural, static and dynamic magnetic properties of dextran coated γ-Fe 2O 3 nanoparticles studied by 57Fe NMR, M?ssbauer, TEM and magnetization measurements

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dc.contributor.authorFardis, M.en
dc.contributor.authorDouvalis, A. P.en
dc.contributor.authorTsitrouli, D.en
dc.contributor.authorRabias, I.en
dc.contributor.authorStamopoulos, D.en
dc.contributor.authorKehagias, Then
dc.contributor.authorKarakosta, E.en
dc.contributor.authorDiamantopoulos, G.en
dc.contributor.authorBakas, T.en
dc.contributor.authorPapavassiliou, G.en
dc.date.accessioned2015-11-24T18:34:47Z
dc.date.available2015-11-24T18:34:47Z
dc.identifier.issn0953-8984-
dc.identifier.urihttps://olympias.lib.uoi.gr/jspui/handle/123456789/16993
dc.rightsDefault Licence-
dc.subjectAverage sizeen
dc.subjectBulk materialsen
dc.subjectCoated nanoparticlesen
dc.subjectDC magnetizationen
dc.subjectEnergy minimaen
dc.subjectHyperfine fielden
dc.subjectInter-particle interactionen
dc.subjectLongitudinal magnetizationen
dc.subjectLow temperature limiten
dc.subjectLow temperature NMRen
dc.subjectLow temperaturesen
dc.subjectMaghemitesen
dc.subjectMagnetic excitationsen
dc.subjectMagnetic nanoparticlesen
dc.subjectMagnetic studiesen
dc.subjectMagnetization measurementsen
dc.subjectMossbaueren
dc.subjectNMR relaxationen
dc.subjectNMR spectrumen
dc.subjectOrders of magnitudeen
dc.subjectSpin-spin relaxation timeen
dc.subjectSsbauer spectroscopiesen
dc.subjectStatic and dynamicen
dc.subjectStructural and magnetic propertiesen
dc.subjectSurface spinsen
dc.subjectTemperature dependenceen
dc.subjectThermal fluctuationsen
dc.subjectZero fieldsen
dc.subjectAssociation reactionsen
dc.subjectDextranen
dc.subjectHigh resolution transmission electron microscopyen
dc.subjectIron oresen
dc.subjectMagnetic propertiesen
dc.subjectMaterials handling equipmenten
dc.subjectNanomagneticsen
dc.subjectNanoparticlesen
dc.subjectNuclear magnetic resonance spectroscopyen
dc.subjectSaturation magnetizationen
dc.subjectTemperatureen
dc.subjectNuclear magnetic resonanceen
dc.subjectferric ionen
dc.subjectferric oxideen
dc.subjectnanoparticleen
dc.subjectarticleen
dc.subjectchemistryen
dc.subjectmagnetismen
dc.subjectMossbauer spectroscopyen
dc.subjecttransmission electron microscopyen
dc.subjectX ray diffractionen
dc.subjectDextransen
dc.subjectFerric Compoundsen
dc.subjectMagnetic Phenomenaen
dc.subjectMagnetic Resonance Spectroscopyen
dc.subjectMicroscopy, Electron, Transmissionen
dc.subjectSpectroscopy, Mossbaueren
dc.subjectX-Ray Diffractionen
dc.titleStructural, static and dynamic magnetic properties of dextran coated γ-Fe 2O 3 nanoparticles studied by 57Fe NMR, M?ssbauer, TEM and magnetization measurementsen
heal.abstractThe structural and magnetic properties and spin dynamics of dextran coated and uncoated γ-Fe 2O 3 (maghemite) nanoparticles have been investigated using high resolution transmission electron microscopy (HRTEM), 57Fe nuclear magnetic resonance (NMR), M?ssbauer spectroscopy and dc magnetization measurements. The HRTEM observations indicated a well-crystallized system of ellipsoid-shaped nanoparticles, with an average size of 10nm. The combined M?ssbauer and magnetic study suggested the existence of significant interparticle interactions not only in the uncoated but also in the dextran coated nanoparticle assemblies. The zero-field NMR spectra of the nanoparticles at low temperatures are very similar to those of the bulk material, indicating the same hyperfine field values at saturation in accord with the performed M?ssbauer measurements. The T 2 NMR spinspin relaxation time of the nanoparticles has also been measured as a function of temperature and found to be two orders of magnitude shorter than that of the bulk material. It is shown that the thermal fluctuations in the longitudinal magnetization of the nanoparticles in the low temperature limit may account for the shortening and the temperature dependence of the T 2 relaxation time. Thus, the low temperature NMR results are in accord with the mechanism of collective magnetic excitations, due to the precession of the magnetization around the easy direction of the magnetization at an energy minimum, a mechanism originally proposed to interpret M?ssbauer experiments in magnetic nanoparticles. The effect of the surface spins on the NMR relaxation mechanisms is also discussed. © 2012 IOP Publishing Ltd.en
heal.accesscampus-
heal.fullTextAvailabilityTRUE-
heal.identifier.primary10.1088/0953-8984/24/15/156001-
heal.identifier.secondaryhttp://www.scopus.com/inward/record.url?eid=2-s2.0-84858743326&partnerID=40&md5=9e613b810385475180a2bb3a50e9d403-
heal.journalNameJournal of Physics Condensed Matteren
heal.journalTypepeer reviewed-
heal.publicationDate2012-
heal.recordProviderΠανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιώνel
heal.typejournalArticle-
heal.type.elΆρθρο Περιοδικούel
heal.type.enJournal articleen

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