Chemisorption on nickel nanoparticles of various shapes: Influence on magnetism

被引:89
作者
Cordente, N
Amiens, C
Chaudret, B
Respaud, M
Senocq, F
Casanove, MJ
机构
[1] CNRS, Chim Coordinat Lab, F-31077 Toulouse, France
[2] LPMC, F-31077 Toulouse, France
[3] CIRIMAT, F-31062 Toulouse, France
[4] CNRS, CEMES, F-31055 Toulouse 04, France
关键词
D O I
10.1063/1.1621081
中图分类号
O59 [应用物理学];
学科分类号
摘要
Nanoparticles of nickel have been obtained in solution through reaction of an organometallic precursor, Ni(COD)(2) (COD=cycloocta-1,5-diene), with dihydrogen, in the presence of various stabilizing agents. X-ray diffraction studies evidence a face-centered-cubic structure for all samples. Spherical isolated superparamagnetic nanoparticles (dsimilar to4.5 nm) are produced in the presence of poly(N-vinylpyrrolid-2-one). They display a magnetization value comparable to that of bulk nickel, as determined from superconducting quantum iinterference device (SQUID) measurements. Exposure of the surface of the nanoparticles to CO, leading to CO coordination as monitored by infrared spectroscopy, or to methanol, strongly reduces their magnetization. This reduction corresponds respectively to one or two magnetically inactive layers of nickel atoms at the nanoparticles surface. The production of elongated nanoparticles was favored when either trioctylphosphineoxide or hexadecylamine (HDA) were used as stabilizing agents. In this case, SQUID measurements show that only HDA preserves the magnetization of the surface. This stabilizing agent was selected for the production of nickel nanorods. The influence of ligands on the effective anisotropy is discussed. (C) 2003 American Institute of Physics.
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页码:6358 / 6365
页数:8
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