Synthesis and magnetic properties of nanocrystalline Ni1-xZnxFe2O4 ferrite

Nanocrystalline Ni1-xZnxFe2O4 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 Ni1-xZnxFe2O4 ferrite powders are obtained by the spraying-coprecipitation method. The grain size is about 30 nm calcined at 600 degrees C for 1.5h. There are a few agglomerates with average sizes below 100nm. The specific saturation magnetization of nanocrystalline Ni1-xZnxFe2O4 ferrite increases with the concent of Zn2+ at room temperature, and maximum sigma(s) is 66.8A center dot m(2)/kg as the content of Zn2+ is around 0.5. When the grain size is 41nm, the coercivity H-c 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.