Influence Of Experimental Conditions On The Magnetic Properties Of Spinel Nanoparticles

Three different kinds of spinel CoFe₂O₄,Fe₃O₄ and Fe₃S₄ nanoparticles were synthesized with different method. The affection of different experimental parameters to the product of crystallite size M?ssbauer spectra and magnetism performance were analyzed, emphatically . Main content is listed as follow:CoFe₂O₄ ferrite nanoparticles of different kinds were synthesized through the control of experimental conditions(synthesis temperature,concentration of Co²⁺ metal ions and the temperature of subsequent heat treatment)with coprecipitation approach. A detailed test and analysis to the sample magnetism performance were implement by XRD, M?ssbauer spectra and VSM. Result show, synthesis temperature and the cobalt ion concentration will improve the microscopic structure and magnetism performance of the product. After the heat treatment, the crystallite size further increases, the proportion of Fe³⁺ ions in A-site and the hyperfine field values,coercivity and saturation magnetization corresponding to A-site and B-site also increase along with it.The affection of additional magnetic field in the preparation process of Fe₃O₄ spinel nanoparticle to the crystallite size, internal ion distribution, coercivity and saturation magnetization were studied. And carring on the concrete analysis to its microscopic structure. The result indicated that, the larger additional magnetic field resulted in the better microstructure and stronger crystallinity. Fe₃O₄ samples produced under 1T magnetic field own the good magnetism performance, its saturation magnetization is 15.3 emu/g, which is much larger than those produced without the magnetic field (saturation magnetization is 6.59 emu/g). Its mainly because, the additional magnetic field strengthened Fe-O-Fe superexchange. Magnetic field induction during synthetic process can improve Fe₃O₄ magnetic properties.By processing hydrothermal, spinel structure semimetal greigite Fe₃S₄ synthesized under the magnetic field induction successfully. Curie temperature TC has been analyzed through XRD and the magnetic measurement under high-vacuum environment.And has calculated the Curie temperature of greigite Fe₃S₄ as 667K precisely.