CoFe2O4/SiO2 nanocomposites by thermal decomposition of some complex combinations embedded in hybrid silica gels |
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Authors: | Paul Barvinschi Oana Stefanescu Thomas Dippong Simona Sorescu Mircea Stefanescu |
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Affiliation: | 1. Faculty of Physics, West University of Timisoara, Bv. V. Parvan No. 4, 300223, Timisoara, Romania 2. Faculty of Chemistry and Chemical Engineering, University “Politehnica” Timisoara, P. Victoriei No. 2, 300006, Timisoara, Romania
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Abstract: | The study reports the preparation of CoFe2O4/SiO2 nanocomposites by a new modified sol–gel method starting from cobalt nitrate, iron nitrate, and diols: 1,2-ethanediol (EG), 1,3-propanediol (1,3PG), and tetraethylorthosilicate (TEOS), for final compositions of 30 %CoFe2O4/70 %SiO2 and 50 %CoFe2O4/50 %SiO2. The method is based on the formation of a Co(II), Fe(III)—carboxylate precursors mixture, during the redox reaction between the NO 3 ? ion and the diol (~140 °C) within the silica gels. The thermal decomposition of these complex combinations takes place at ~300 °C leading to the corresponding amorphous metal oxides within the pores of the hybrid gels. Depending on the subsequent thermal treatment, CoFe2O4 can be obtained as single phase or in a mixture with Co2SiO4. The CoFe2O4 crystallites sizes are in the nanometer range (3–10 nm). The obtained nanocomposites have a hard magnet behavior, as a result of the high anisotropy of CoFe2O4 having large hysteresis cycles. |
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