Interface controlled electrical and magnetic properties in Fe-Fe3O4-silica gel nanocomposites

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dc.contributor.author Roy, Saibal
dc.contributor.author Das, D.
dc.contributor.author Chen, J.
dc.contributor.author Chakravorty, D.
dc.date.accessioned 2017-10-11T11:55:22Z
dc.date.available 2017-10-11T11:55:22Z
dc.date.issued 2002-04
dc.identifier.citation Das, D., Roy, S., Chen, J. and Chakravorty, D. (2002) 'Interface controlled electrical and magnetic properties in Fe-Fe3O4-silica gel nanocomposites', Journal of Applied Physics, 91(7), pp. 4573-4579. doi:10.1063/1.1454197 en
dc.identifier.volume 91 en
dc.identifier.issued 7 en
dc.identifier.startpage 4573 en
dc.identifier.endpage 4579 en
dc.identifier.issn 0021-8979
dc.identifier.uri http://hdl.handle.net/10468/4859
dc.identifier.doi 10.1063/1.1454197
dc.description.abstract Iron nanoparticles with a shell of Fe3O4Fe3O4 phase with a total diameter of 5.3 nm have been grown within a silica gel matrix in the percolative configuration by suitable reduction followed by oxidation treatments. dc electrical resistivity measurements were carried out in the temperature range 80–300 K. The resistivity of the nanocomposites was found to be about 7 orders of magnitude lower than that of the reference gel. The electrical conduction has been explained on the basis of a small polaron hopping mechanism. The activation energy in the case of the composites was calculated from experimental data to be about one-fifth that for the reference sample. An interfacial amorphous phase is believed to cause such reduction in resistivity. The effective dielectric constant of this phase was estimated to be about four times that of the reference glass. Magnetization measurements on these specimens were carried out in the temperature range 5–300 K both in zero field cooled and field cooled states. A peak in the magnetization at ∼120 K was ascribed to an order–disorder (Verwey) transition. Another peak at ∼55 K was explained as arising due to a spin glass like disorder at the interface between the ferromagnetic iron ores and the ferrimagnetic Fe3O4Fe3O4 shell. A loop shift was observed as a result of the spin freezing below this temperature. en
dc.description.sponsorship Ministry of Science and Technology of the People's Republic of China (research Grant No. NSC 88-2111-M-002-021) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher American Institute of Physics en
dc.rights © 2002, American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared as Das, D., Roy, S., Chen, J. and Chakravorty, D. (2002) 'Interface controlled electrical and magnetic properties in Fe– Fe3O4 –silica gel nanocomposites', Journal of Applied Physics, 91(7), pp. 4573-4579. doi:10.1063/1.1454197 and may be found at http://dx.doi.org/10.1063/1.1454197 en
dc.subject Iron en
dc.subject Nanoparticles en
dc.subject Silica gel en
dc.title Interface controlled electrical and magnetic properties in Fe-Fe3O4-silica gel nanocomposites en
dc.type Article (peer-reviewed) en
dc.internal.authorcontactother Saibal Roy, Tyndall Microsystems, University College Cork, Cork, Ireland. +353-21-490-3000 Email: saibal.roy@tyndall.ie en
dc.internal.availability Full text available en
dc.date.updated 2017-10-11T09:25:03Z
dc.description.version Published Version en
dc.internal.rssid 259773468
dc.contributor.funder Department of Science and Technology, Ministry of Science and Technology en
dc.contributor.funder Ministry of Science and Technology of the People's Republic of China en
dc.description.status Peer reviewed en
dc.identifier.journaltitle Journal of Applied Physics en
dc.internal.copyrightchecked Yes en
dc.internal.licenseacceptance Yes en
dc.internal.IRISemailaddress saibal.roy@tyndall.ie en


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