针状纳米Ni_(0.5)Zn_(0.5)Fe_2O_4的沉淀/凝胶-溶胶法制备及性能

Spiculate Nano-Ni_(0.5)Zn_(0.5)Fe_2O_4: Preparation by Precipitation/Sol-Gel Method and Characterization

以FeCl2、Zn(NO3)2、Ni(NO3)2和NaOH为原料,借助针状α-FeOOH做为中间体,用共沉淀法和柠檬酸法相结合的方法制得掺有镍和锌的针状纳米α-FeOOH,在其表面包裹镍和锌的柠檬酸配合物后,经热处理制得了针状的纳米Ni0.5Zn0.5Fe2O4,并通过控制共沉淀法过程中镍和锌的掺入量,有效地控制了针状纳米Ni0.5Zn0.5Fe2O4的粒径和长径比。利用XRD、TEM对样品的物相﹑形状和粒径进行表征。结果表明:共沉淀过程中Ni和Zn的掺入量对制备的Ni0.5Zn0.5Fe2O4的形状有重要的影响,随着镍和锌的掺入量的增加,制得的针状纳米Ni0.5Zn0.5Fe2O4的直径逐渐减小,长径比先增加后减小,当nNi∶nZn∶nFe=0.3∶0.3∶2时,样品的长径比达到最大为20左右。利用振荡样品磁强计(VSM)对样品进行磁性能研究,结果表明针状Ni0.5Zn0.5Fe2O4矫顽力主要取决于样品的各向异性,随着样品的长径比增加,各向异性增加,矫顽力增加。随温度的提高,晶体结构趋于完善,样品的矫顽力下降。

The Ni and Zn-doped spiculate α-FeOOH were prepared by the coprecipitation method and citric acid method using FeCl2、Zn（NO3）2、Ni（NO3）2 and NaOH as raw materials and spiculate α-FeOOH as the intermediate. Then they successively were enwrapped by citric acid complex of the Ni and Zn, and heat treated to get spiculate nano-Ni0.5Zn0.5Fe2O4. The particle size and ratio of length to diameter of spiculate nano-Ni0.5Zn0.5Fe2O4 were controlled by the doped mass of Ni and Zn in the coprecipitation process. The phase, morphology, and particle diameter of samples were studied by XRD and TEM. It is indicated that the doped mass of Ni and Zn has great effect on the morphology of Ni0.5Zn0.5Fe2O4. With the increase in Ni and Zn doped mass, the diameter of the nano-Ni0.5Zn0.5Fe2O4 reduces gradually, the ratio of length to diameter first increases and then decreases. As the molar ratio of nNi∶nZn∶nFe equals to 0.3∶0.3∶2, the ratio of length to diameter is at maximum（about 20）. The magnetic properties of samples were studied by vibrating sample magnetometer（VSM）. It is found that the coercivity of the Ni0.5Zn0.5Fe2O4 sample depends mainly on the anisotropy of the samples. With the increase in the ratio of length to diameter, the anisotropy and coercivity of the samples increase. With the increase in the calcination temperature, the coercivity of the samples reduces and crystal tends to be perfect.