Structure and magnetic properties of Gd nanoparticles and carbon coated Gd/GdC2 nanocapsules
Structure and magnetic properties of Gd nanoparticles and carbon coated Gd/GdC2 nanocapsules
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DOI：
10.1063/1.1619192
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发表时间：
2003-10
影响因子：
3.2
通讯作者：
P. Si;I. Škorvánek;J. Kováč;D. Geng;X. Zhao;Zhidong Zhang
中科院分区：
文献类型：
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作者：
P. Si;I. Škorvánek;J. Kováč;D. Geng;X. Zhao;Zhidong Zhang
分别在Ar和甲烷中用电弧放电法制备了Gd纳米粒子和Gd/GdC2纳米碳包覆纳米胶囊。X-射线衍射仪检测到Gd纳米粒子中有Gd氧化物的存在，氧分析和X-射线光电子能谱证明了金属Gd的存在。X射线衍射仪检测到纳米胶囊中GdC2和Gd的存在。观察到纳米颗粒(直径大于20 nm)和纳米胶囊的壳/核结构。在25K以上的磁化强度数据，当作为mU(0)H/T的函数时，落在一条普适曲线上，而4.2K时的磁化曲线偏离普适曲线的原因是Gd小颗粒的超顺磁性-铁磁性转变。磁化强度与温度的关系支持非常微小的Gd纳米粒子的理论预测。这些纳米胶囊中金属Gd的存在导致了在4.2K时相对较高的磁化强度，约为60.5Am2/kg，而不含金属Gd的碳化镓纳米胶囊的磁化强度较高。讨论了Gd(O)纳米粒子和Gd(C)纳米胶囊存在类自旋玻璃态的可能性。(C)2003年美国物理研究所。
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 mu(0)H/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. (C) 2003 American Institute of Physics.