Relationship between nanoparticle growth and magnetic properties of magnetic nanocomposites

Ortega, Daniel; Garitaonandia, J. S.; Ramírez‐del‐Solar, M.; Barrera-Solano, C.; Domínguez, M.

doi:10.1016/j.jnoncrysol.2008.06.110

Cited by 4 publications

(3 citation statements)

References 5 publications

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“…It can be stated that, when the sample processing include a washing step after a short maturation period, hematite conversion is avoided, as this is also confirmed by electron diffraction patterns. In previous HRTEM studies [19], we have shown that amorphous clusters, precursor of maghemite nanoparticles, are formed at 300 • C and that the first crystalline nuclei are detected after 500 • C treatment. On the other hand, when the washing step is not carried out, a mixture of α and γ -Fe 2 O 3 is identified [23].…”

Section: Discussionmentioning

confidence: 69%

“…Nevertheless, due to the similarities between the cubic and the tetragonal groups, it is not possible to distinguish whether both phases are present or not. The HRTEM images also reveal no specific orientations in attachments between particles [19]. Iron oxide nanoparticles can be better distinguished from the softer silica matrix through HAADF images because of the significant differences in the local atomic number, providing a higher degree of confidence and detail than those obtained in conventional transmission images.…”

Section: Resultsmentioning

confidence: 92%

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Maghemite–silica nanocomposites: sol–gel processing enhancement of the magneto-optical response

et al. 2008

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The preparation and processing of maghemite-silica gel nanocomposites have been investigated in order to maximize their magneto-optical response for magnetic field sensing applications. In situ precipitation of maghemite nanoparticles from an iron salt precursor during the sol-gel processing of the silica matrix has been carried out while controlling the time, temperature, and environment at each step of the whole process. In this paper, the nanostructural, magnetic, and magneto-optical properties of these materials are correlated with the processing path followed, from the starting sol to the partially densified monolith. Results demonstrate that introducing a washing treatment prevents the formation of hematite phase as well as an excessive particle agglomeration. Different processing conditions of identical sols may lead to nanocomposites with a Verdet constant at low magnetic fields (0.01 T) ranging from 200 to 950 rad T(-1) m(-1), which is the typical value of commercial terbium gallium garnets used in Faraday rotators.

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Section: Discussionmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 92%

Maghemite–silica nanocomposites: sol–gel processing enhancement of the magneto-optical response

et al. 2008

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“…In this respect, uniform dispersion of iron oxide nanoparticles in organic polymers or inorganic silica matrix is particularly promising. Among the others, sol-gel processes are extensively used for the preparation of iron(III) oxide nanoparticles (c-Fe 2 O 3 ) in organic polymers [5,15] or in inorganic silica matrix [16][17][18][19][20] by incorporation of Fe 3+ ions during synthesis and subsequent thermal-treatments. The porous nature of amorphous silica matrix provides nucleating sites for guest Fe 3+ ions and minimize the aggregation phenomena imposing upper limit to the size and isolate particles from each other.…”

Section: Introductionmentioning

confidence: 99%