Fabrication of cobalt nano-particles by pulsed wire evaporation method in nitrogen atmosphere

This work reports the use of pulsed wire evaporation (PWE) method to prepare cobalt (Co) nano-particles. The effect of charging voltage on the average particle size and particle morphology was studied. The Co nano-panicles were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and BET surface area analysis. SEM and TEM observations showed that the Co particles had spherical shape and were linked to each other because of their magnetic property. The XRD analyses confirmed that Co nano-particles had FCC structure without any presence of impurity phase. Average particle size was calculated by three methods; TEM, BET and XRD. The results showed that the particle size decreased with increasing charging voltage and then attempted to saturate, which was explained with crystallite size of the Co wire, superheating factor and specific energy input into the wire. (C) 2012 Elsevier B.V. All rights reserved.