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- Title
Thermal behavior of CoFeO/SiO nanocomposites obtained by a modified sol-gel method.
- Authors
Dippong, Thomas; Levei, Erika; Cadar, Oana; Goga, Firuta; Borodi, Gheorghe; Barbu-Tudoran, Lucian
- Abstract
The thermal behavior of CoFeO/SiO nanocomposites obtained by direct synthesis starting from nonahydrate ferric nitrate and hexahydrate cobalt nitrate in different ratios with and without the addition of 1,4-butanediol was studied. For the synthesis of CoFeO ( x = 0.5-2.5) dispersed in the silica matrix a wide Co/Fe molar ratio was used. The decomposition processes, formation of crystalline phases, gases evolvement and mass changes during gels annealing at different temperatures were assessed by thermal analysis. The absence of succinate precursor and a low mass loss were observed in the case of the gel obtained in the absence of 1,4-butanediol. In case of gels obtained using a stoichiometric ratio of Co/Fe, no clear delimitation between Co and Fe succinates was observed, while for samples with a Fe or Co excess, the formation of the two succinates was observed. The evolution of the crystalline phase after annealing (673, 973 and 1273 K) investigated by X-ray diffraction analysis and Fourier transformed infrared spectrometry revealed that in samples with Fe excess, stoichiometric Fe/Co ratio or low Co excess, the cobalt ferrite (CoFeO) was obtained as a single phase, while in samples with higher cobalt excess, olivine (CoSiO) as a main phase, cobalt oxide and CoFeO as secondary phases were obtained after annealing at 1273 K. The SEM images confirmed the nanoparticles embedding in the silica matrix, while the TEM and X-ray diffraction data showed that the obtained nanoparticles' size was below 10 nm in most samples.
- Subjects
COBALT alloys; IRON oxides; NANOCOMPOSITE materials; SOL-gel processes; TEMPERATURE measurements
- Publication
Journal of Thermal Analysis & Calorimetry, 2017, Vol 128, Issue 1, p39
- ISSN
1388-6150
- Publication type
Article
- DOI
10.1007/s10973-016-5930-8