Preparation Characterization And Magnetic Properties Of One-dimensional Magnetic Alloy/Spinel Ferrite Composite Nanostructures

A series of Fe-Ni alloy/nickel ferrite, CoFe2alloy/cobalt ferrite and Fe-Co-Nialloy/Co-Ni ferrite composite nanofibers with average diameters of60–80nm weresuccessfully prepared using electrospinning combined hydrogen-thermal reduction method.The effects of the reduction temperature, reduction time and calcination temperature offerrite nanofibers on the crystal structure, phase composition, morphology and magneticproperties of the reduced products are systematicly investigated.Fe-Ni alloy phase within Fe-Ni alloy/nickel ferrite composite nanofibers consists of theface centered cubic and body centered cubic structures. With the increase of reductiontemperature, the content of Fe-Ni alloys in products increases, and Fe-Ni alloys still have aBCC structure to FCC structure dominant transition in phase composition. The specificsaturation magnetization, remnant magnetization and coercivity of the reduced productsincrease initially with increasing reduction temperature, reaching their maximum values of177.9A·m²·kg^-1,54.9A·m²·kg^-1and42.7kA·m^-1, respectively, when the reductiontemperature is320℃, namely, the alloy content is about82wt%, and then decrease withfurther increase in reduction temperature.For the preprared CoF2alloy/cobalt ferrite composite nanofibers, CoFe2alloy phase issingle body centered cubic structure. With increasing reduction temperature, the CoFe2alloycontent in the reduced products increases, and both the specific saturation magnetization andremnant magnetization exhibit an increase tendency whereas the coercivity graduallydecreases. As the reduction temperature is300℃, with the increase of calcinationtemperature of cobalt ferrite nanofibers, the specific saturation magnetization and remnantmagnetization of the reduced products decrease, while the corresponding coercivity firstlydecrease and then increase after reaching a minimum value at the calcination temperature of600℃, which may be attributed to the enhancement of the magnetic exchange couplinginteraction between the two magnetic phases in the sample.Fe-Co-Ni alloy/Co-Ni ferrite composite nanofibers consist of face centered cubic spinel structure ferrite and body centered cubic structure alloy. With the reduction temperaturesincreasing, the Fe-Co-Ni alloy content of the reduced products increases, the specificsaturation magnetization and remnant magnetization increase, while coercivity decreases.As the reduction temperature is300℃, the content of Fe-Co-Ni alloys in products increaseswith longer reduction time, but the degree of the reduction is basicly stable above1h. Thechange tendency of magnetic properties with reduction time is similar to that withtemperature.