钴铁氧体纳米晶粒的结构及磁特性研究

Studies on the structure and magnetic properties of Co_xFe_(3-x)O_(4) nanoparticles

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HE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。

Cobah ferrite CoxFe3-xO4 （ 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 CoxFe3-xO4 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） CoxFe3-xO4 phase and α- Fe2O3 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 σs was attained at the x = 0.8. In the range of x = 0.5 - 0.8, the coercivity Hc decreases with the increase of x , then climbs up rapidly. Higher or s and Hc can be achieved simultaneously in the vicinity of x = 1.0.