Skip to main content Accessibility help
×
Home
Hostname: page-component-78bd46657c-lpzrl Total loading time: 0.296 Render date: 2021-05-06T10:58:30.613Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": false, "newCiteModal": false, "newCitedByModal": true }

A Transmission Electron Microscopy Study of Fe-Co Alloy Nanoparticles in Silica Aerogel Matrix Using HREM, EDX, and EELS

Published online by Cambridge University Press:  16 March 2009

Andrea Falqui
Affiliation:
Dipartimento di Scienze Chimiche and INSTM, Università di Cagliari, S.P. Monserrato-Sestu Km 0.700, 09042 Monserrato, Cagliari, Italy Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
Anna Corrias
Affiliation:
Dipartimento di Scienze Chimiche and INSTM, Università di Cagliari, S.P. Monserrato-Sestu Km 0.700, 09042 Monserrato, Cagliari, Italy
Mhairi Gass
Affiliation:
SuperSTEM, Daresbury Laboratory, Keckwick Lane, Daresbury, Cheshire WA4 4AD, UK
Gavin Mountjoy
Affiliation:
Dipartimento di Scienze Chimiche and INSTM, Università di Cagliari, S.P. Monserrato-Sestu Km 0.700, 09042 Monserrato, Cagliari, Italy
Corresponding
E-mail address:

Abstract

Magnetic nanocomposite materials consisting of 5.5 wt% Fe-Co alloy nanoparticles in a silica aerogel matrix, with compositions FexCo1−x of x = 0.50 and 0.67, have been synthesized by the sol-gel method. The high-resolution transmission electron microscopy images show nanoparticles consisting of single crystal grains of body-centered cubic Fe-Co alloy, with typical crystal grain diameters of approximately 4 and 7 nm for Fe0.5Co0.5 and Fe0.67Co0.33 samples, respectively. The energy dispersive X-ray (EDX) spectra summed over areas of the samples gave compositions FexCo1−x with x = 0.48 ± 0.06 and 0.68 ± 0.05. The EDX spectra obtained with the 1.5 nm probe positioned at the centers of ∼20 nanoparticles gave slightly lower concentrations of Fe, with means of ⟨x⟩ = 0.43 ± 0.01 and ⟨x⟩ = 0.64 ± 0.02, respectively. The Fe0.5Co0.5 sample was studied using electron energy loss spectroscopy (EELS), and EELS spectra summed over whole nanoparticles gave x = 0.47 ± 0.06. The EELS spectra from analysis profiles of nanoparticles show a distribution of Fe and Co that is homogeneous, i.e., x = 0.5, within a precision of at best ±0.05 in x and ±0.4 nm in position. The present microscopy results have not shown the presence of a thin layer of iron oxide, but this might be at the limit of detectability of the methods.

Type
Materials Applications
Copyright
Copyright © Microscopy Society of America 2009

Access options

Get access to the full version of this content by using one of the access options below.

Footnotes

Permanent address: School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH, UK

References

Abeles, B. (1976). Granular metal films. In Applied Solid State Science, Wolfe, R. (Ed.), pp. 1117. New York: Academic Press.Google Scholar
Brinker, C.J. & Scherer, G.W. (1990). Sol-Gel Science. San Diego, CA: Academic Press.Google Scholar
Carta, D., Mountjoy, G., Gass, M., Navarra, G., Casula, M.F. & Corrias, A. (2007). Structural characterization study of FeCo alloy nanoparticles in a highly porous aerogel silica matrix. J Chem Phys 127, 204705.CrossRefGoogle Scholar
Casu, A., Casula, M.F., Corrias, A., Falqui, A., Loche, D., Marras, S. & Sangregorio, C. (2008). The influence of composition and porosity on the magnetic properties of FeCo-SiO2 nanocomposite aerogels. Phys Chem Chem Phys 10, 10431052.CrossRefGoogle ScholarPubMed
Casula, M.F., Concas, G., Congiu, F., Corrias, A., Falqui, A. & Spano, G. (2005). Near equiatomic FeCo nanocrystalline alloy embedded in an alumina aerogel matrix: Microstructural features and related magnetic properties. J Phys Chem B 109, 2388823895.CrossRefGoogle Scholar
Casula, M.F., Loche, D., Marras, S., Paschina, G. & Corrias, A. (2007). Role of urea in the preparation of highly porous nanocomposite aerogels. Langmuir 23, 35093512.CrossRefGoogle ScholarPubMed
Cliff, G. & Lorimer, G.W. (1975). The quantitative analysis of thin specimens. J Microsc 103, 203207.CrossRefGoogle Scholar
Egerton, R.F. (1996). Electron Energy-Loss Spectroscopy in the Electron Microscope, pp. 210216. New York: Plenum Press.CrossRefGoogle Scholar
Ennas, G., Casula, M.F., Falqui, A., Gatteschi, D., Marongiu, G., Piccaluga, G., Sangregorio, C. & Pinna, G. (2001). Nanocrystalline iron-cobalt alloys supported on a silica matrix prepared by the sol-gel method. J Non-Cryst Solids 293-295, 19.CrossRefGoogle Scholar
Falqui, A., Serin, V., Calmels, L., Snoeck, E., Corrias, A. & Ennas, G. (2003). EELS investigation of FeCo/SiO2 nanocomposites. J Microsc 210, 8088.CrossRefGoogle ScholarPubMed
Gich, M., Casas, L., Roig, A., Molins, E., Sort, J., Surinach, S., Baro, M.D., Munoz, J.S., Morellon, L., Ibarra, M.R. & Nogue, S. (2003). High-coercivity ultralight transparent magnets. Appl Phys Lett 82, 43074309.CrossRefGoogle Scholar
Guillermet, A.F. (1988). Critical evaluation of the thermodynamic properties of the Fe-Co system. High Temp High Press 19, 477499.Google Scholar
Husing, N. & Schubert, U. (1998). Aerogels airy materials: Chemistry, structure, and properties. Angew Chem Int Ed 37, 2245.3.0.CO;2-I>CrossRefGoogle ScholarPubMed
Li, J.S., Mirzamaani, M., Bian, X.P., Doerner, M., Duan, S.L., Tang, K., Toney, M., Arnoldussen, T. & Madison, M. (1999). 10 Gbit/in.2 longitudinal media on a glass substrate. J Appl Phys 85, 42864291.CrossRefGoogle Scholar
MacLaren, J.M., Schulthess, T.C., Butler, W.H., Sutton, R. & McHenry, M.J. (1999). Electronic structure, exchange interactions, and Curie temperature of FeCo. J Appl Phys 85, 48334835.CrossRefGoogle Scholar
Moreno, E.M., Zayat, M., Morales, M.P., Serna, C.J., Roig, A. & Levy, D. (2002). Preparation of narrow size distribution superparamagnetic gamma-Fe2O3 nanoparticles in a sol-gel transparent SiO2 matrix. Langmuir 18, 49724978.CrossRefGoogle Scholar
Paduani, C. & Krause, J.C. (1999). Electronic structure and magnetization of Fe-Co alloys and multilayers. J Appl Phys 86, 578583.CrossRefGoogle Scholar
Pierre, A.C. & Pajonk, G.M. (2002). Chemistry of aerogels and their applications. Chem Rev 102, 42434265.CrossRefGoogle ScholarPubMed
Saad, A.M., Mazanik, A.V., Kalinin, Y.E., Fedotova, J.A., Fedotov, A.K., Wrotek, S., Sitnikov, A.V. & Svito, I.A. (2004). Structure and electrical properties of CoFeZr-aluminium oxide nanocomposite films. Rev Adv Mater Sci 8, 152157.Google Scholar
Williams, D.B. & Carter, C.B. (1996). Transmission Electron Microscopy, vol. 4, pp. 608611. New York: Plenum Press.CrossRefGoogle Scholar

Send article to Kindle

To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

A Transmission Electron Microscopy Study of Fe-Co Alloy Nanoparticles in Silica Aerogel Matrix Using HREM, EDX, and EELS
Available formats
×

Send article to Dropbox

To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

A Transmission Electron Microscopy Study of Fe-Co Alloy Nanoparticles in Silica Aerogel Matrix Using HREM, EDX, and EELS
Available formats
×

Send article to Google Drive

To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

A Transmission Electron Microscopy Study of Fe-Co Alloy Nanoparticles in Silica Aerogel Matrix Using HREM, EDX, and EELS
Available formats
×
×

Reply to: Submit a response


Your details


Conflicting interests

Do you have any conflicting interests? *