纳米囊
超顺磁性
钆
磁化
纳米颗粒
材料科学
碳化物
铁磁性
分析化学(期刊)
化学工程
纳米技术
化学
复合材料
凝聚态物理
有机化学
磁场
冶金
物理
工程类
量子力学
作者
P. Z.,I. Škorvánek,J. Kováč,Dongling Geng,Xiaowei Zhao,Zhirong Zhang
摘要
Gd nanoparticles and carbon coated Gd/GdC2 nanocapsules have been prepared by means of arc discharge in argon and methane, respectively. In the Gd nanoparticles, gadolinium oxide was detected by x-ray diffraction, while the presence of metallic gadolinium was proved by oxygen analysis and x-ray photoelectron spectra. In the nanocapsules, the existence of GdC2 and Gd was detected by x-ray diffraction. Shell/core structures were observed for either the nanoparticles (with diameters larger than 20 nm) or the nanocapsules. The magnetization data above 25 K, when scaled as a function of μ0H/T, fall on a universal curve while the deviation of the magnetization curves at 4.2 K from the universal curves was ascribed to the superparamagnetism–ferromagnetism transition of small Gd particles. The temperature dependence of magnetization supports the theoretical predictions for very tiny Gd nanoparticles. The presence of metallic Gd in these nanocapsules results in comparatively high magnetization of about 60.5 A m2/kg at 4.2 K, compared with the carbon-coated gadolinium carbide nanocapsules without the metallic Gd core. The possibility of the existence of the spin-glass-like state is discussed for Gd(O) nanoparticles and Gd(C) nanocapsules.
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