Investigations on magnetic properties and structure for carbon encapsulated nanoparticles of Fe, Co, Ni

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2000-06, Vol.286 (1), p.157-160
• Main Authors: Sun, Xiangcheng, Gutierrez, A, Yacaman, M.Jose, Dong, Xinglong, Jin, Shouri
• Format: Article
• Language: English
• Subjects: Amorphous and nanocrystalline magnetic materials; quasicrystals; Amorphous and quasicrystalline magnetic materials; Applied sciences; Carbon encapsulated nanoparticles; Clusters, nanoparticles, and nanocrystalline materials; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Magnetic properities; Magnetic properties and materials; Metals. Metallurgy; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Physics; Structure of solids and liquids; crystallography; Studies of specific magnetic materials; Superparamagnetic
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/S0921-5093(00)00628-6

In the present work, experiments aim at the encapsulation of foreign materials within hollow graphitic cage have been carried out for iron group metals (Fe, Co, Ni) using a modified arc-discharge (carbon arc) reactor. HRTEM (high resolution transmission electron miscroscope), and XRD (X-ray diffractometer) studies, for three carbon encapsulated materials, showing nanoparticles of both a metallic phase (α-Fe, γ-Fe; hcp-Co, fcc-Co; fcc-Ni) and also a carbide phase (M 3C, M=Fe, Co, Ni) are encapsulated in graphitic carbon. The magnetic measurement for the three as-made nanoparticles, indicating that the values of saturation magnetic moment of three nanoparticle are 37.6, 55.5 and 15.7% of the bulk ferromagnetic elements counterparts, respectively. The different comparison values ( M r/ M s) of remanent magnetization ( M r) and saturation magnetization ( M s) suggest, the encapsulated Fe and Co nanoparticles are shown to be ferromagnetic with a ratio of remnant to saturation magnetization M r/ M s∼0.3; whereas, the encapsulated Ni nanoparticles exhibits superparamagnetic behavior at room temperature.