Magnetic properties and microstructure of cobalt nanoparticles in a polymer film

✍ Scribed by I.-W. Park; M. Yoon; Y.M. Kim; Y. Kim; H. Yoon; H.J. Song; V. Volkov; A. Avilov; Y.J. Park

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 429 KB
• Volume: 126
• Category: Article
• ISSN: 0038-1098
• DOI: 10.1016/s0038-1098(03)00189-3

✦ Synopsis

Superparamagnetic properties of self-aggregated cobalt nanoparticles in the perfluorinated sulfo-cation membrane (MF-4SK) prepared by ion-exchange method were investigated by transmission electron microscopy (TEM) and superconducting quantum interference device (SQUID) magnetometry at various temperatures. Our experimental results show that cobalt nanoparticles in MF-4SK exhibit superparamagnetic properties above the blocking temperature ðT B Þ; which varies from , 80 to , 300 K depending on the cobalt concentration at 100 Oe applied field. The average particle radius of 3.8 nm inferred from Langevin function fit for the concentration of 7.8 £ 10 19 cobalt atoms per 1 g of polymer film is in good agreement with TEM observation. This experimental evidence suggests that cobalt nanoparticles in the polymer film obey a single-domain theory. The results are discussed in the light of current theory for the superparamagnetic behavior of magnetic nanoparticles.