Abstract:

Nanocrystalline Ni_1-x Zn_xFe₂O₄ ferrite with 0≤x≤1, was successfully prepared by a spraying-coprecipitation method. The microstructure was investigated by using TG-DSC, XRD, SEM, TEM as well as BET. Magnetic properties were measured with a vibrating sample magnetometer (VSM) at room temperature. The results show that uniform and fine nanocrystalline Ni_1-xZn_xFe₂O₄ ferrite powders are obtained by the spraying-coprecipitation method. The grain size is about 30 nm calcined at 600 for 1.5h. There are a few agglomerates with average sizes below 100nm. The specific saturation magnetization of nanocrystallineNi_1-x Zn_xFe₂O₄ ferrite increases with the concent of Zn²⁺ at room temperature, and maximum σs is 66.8A·m²/kg as the content of Zn²⁺ is around 0.5. When the grain size is 41nm, the coercivity Hc of nanocrystalline Ni0.5Zn0.5Fe2O4 ferrite arrives at 5.06kA/m, and then it decreases with the increase of the grain size. The results may be explained in terms of intense random magnetocrystalline anisotropy model in nanocrystalline materials.

Key words: nanocrystalline materials, Ni1-xZnxFe2O4 ferrite, spraying-coprecipitation method, magnetic properties