钴铁氧体纳米晶粒的结构及磁特性研究

采用化学共沉法制备了纳米尺度的钴铁氧体粉料,并在1260~1340℃温度下进行了退火处理,利用X射线衍射仪(XRD)、振动样品磁强计(VSM)对样品的结构和磁性进行了测量和分析.实验结果表明,在钴高含量(x≥0.7)时样品形成了单一的具有尖晶石结构的钴铁氧体,而钴含量x<0.7时样品生成了尖晶石结构的钴铁氧体相和α-Fe2O3相;CoxFe3-xO4的比饱和磁化强度σS随x的增加呈现出了先增后减的趋势,在x=0.8时出现峰值;在x=0.5~0.8范围内,矫顽力Hc随钴含量的增加有所下降,随后迅速增加,在x=1.0附近能同时得到较大的σS和Hc值.

Studies on the structure and magnetic properties of CoxFe3-xO4 nanoparticles

Cobalt ferrite Co_xFe_(3-x)O_4(x=0.2~1.0) nanocrystalline powders were prepared by chemical coprecipitation method and annealed at temperatures from 1260℃ to 1340℃ in air,The structure and magnetic properties of the samples are measured and analyzed through the X-ray diffraction(XRD)patterns and vibrating sample magnetometer(VSM).The experimental results show that monophase Co_xFe_(3-x)O_4 ferrites with a spinel structure was formed at high Co~(2+) content(x≥0.7),while at the low Co~(2+) content((x<0.7))Co_xFe_(3-x)O_4 phase and α-Fe_2O_3 phase was obtained at the same time,the specific saturation magnetization climbs up at first and falls down with the increase of the cobalt content.The maximum of σ_S was attained at the x=0.8.In the range of x=0.5~0.8,the coercivity H_c decreases with the increase of x,then climbs up rapidly.Higher σ_S and H_c can be achieved simultaneously in the vicinity of x=1.0.