Oxidation effect in cobalt nanoparticles magnetic fluids

Jong Soo Hong, Jeffrey Pyun, Yong Wook Park, Chul Sung Kim, In Bo Shim

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Cobalt nanoparticles were synthesized by modified thermal decomposition and oxidized in the condition of solution. Crystal structure of fabricated cobalt nanoparticles is determined to be cubic of Fm-3m space group from X-ray diffraction (XRD) measurement. Microstructure of cobalt nanoparticles after the oxidation process show core-shell structure. The particle size and thickness of oxide shell can be controlled by oxidation temperature. The shell thickness of cobalt nanoparticles after the oxidation at 300° C is 4.7 nm, when compared to those oxidized at 250° C with the shell thickness of 2.4 nm due to the change in the oxidation temperature. The magnetic properties of cobalt particles have been measured with VSM. Our results show that cobalt metal (core)/cobalt oxide (shell) has two magnetic behaviors of ferromagnetic and antiferromagnetic properties in magnetic fluid.

Original languageEnglish (US)
Article number4957721
Pages (from-to)2464-2466
Number of pages3
JournalIEEE Transactions on Magnetics
Issue number6
StatePublished - Jun 2009


  • Cobalt nanoparticles
  • Core-shell structure
  • Magnetic fluid
  • Oxidation process

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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