Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin, 13083-859, Campinas, SP, Brazil.
Nanoscale. 2014 Jan 7;6(1):352-7. doi: 10.1039/c3nr04926d. Epub 2013 Nov 7.
Ni(1-x)FexO nanoparticles have been obtained by the co-precipitation chemical route. X-ray diffraction analyses using Rietveld refinement have shown a slight decrease in the microstrain and mean particle size as a function of the Fe content. The zero-field-cooling (ZFC) and field-cooling (FC) magnetization curves show superparamagnetic behavior at high temperatures and a low temperature peak (at T = 11 K), which is enhanced with increasing Fe concentration. Unusual behavior of the coercive field in the low temperature region and an exchange bias behavior were also observed. A decrease in the Fe concentration induces an increase in the exchange bias field. We argue that these behaviors can be linked with the strengthening of surface anisotropy caused by the incorporation of Fe ions.
采用共沉淀化学路线制备了 Ni(1-x)FexO 纳米粒子。使用 Rietveld 精修的 X 射线衍射分析表明，随着 Fe 含量的增加，微应变和平均粒径略有减小。零场冷却 (ZFC) 和场冷却 (FC) 磁化曲线在高温下表现出超顺磁性行为，并且在低温下出现一个峰值（在 T = 11 K 时），随着 Fe 浓度的增加而增强。在低温区观察到矫顽力的异常行为和交换偏置行为。随着 Fe 浓度的降低，交换偏置场增加。我们认为这些行为可以与由于掺入 Fe 离子而导致的表面各向异性增强相关联。
