Preparation of spinel ferrite CoFe2O4 fibres by organic gel-thermal decomposition process

Functional spinel ferrite fibers are attractive for high-tech applications. The spinel CoFe2O4 fibres have been prepared by the organic gel-thermal decomposition process from starting materials of Co, Fe nitrate salts and citric acid. The gel spinning performance was a major factor for preparation of uniform gel fibrous precursors. It was related to the citrate-metal complex structure, and linear-type structural molecule [(C6H6O7)(4)CoFe2](n), for the gel precursor was formed during the complexation reaction between the citric acid and metal ions at pH 5.5. As a result, the gel composed of these linear-type molecules exhibited a good spinning performance. The composition, structure of the gel precursors and products derived from thermal decomposition of these precursors were characterized by FTIR, XRD and SEM. The thermal decomposition process of the gel precursors was investigated by TG-DSC. The prepared spinel CoFe2O4 fibres having grain sizes of 40 similar to 50 nm possess the diameters of about 1 mu m, spect ratios up to 1x10(6) (length/diameter), a saturation magnetization value of 81.97 A.m(2)/kg and a coercivity value of 1041.47 X 79.6 A/m.