Surface oxidation of iron nanoparticles

The electrochemical reaction between aqueous ferric chloride solution and M g powder has been carried out in open atmosphere to prepare iron nanopartic les. Since iron particles get easily oxidised to alpha -Fe2O3, gamma -Fe2O3 and Fe3O4, the final product contains the oxides in different proportions with different dimensions depending on the concentration of the FeCl3 solut ion in the electrochemical reaction. The final products were characterised using X-ray and Mossbauer spectroscopy. The results may be summarised as: ( 1) concentrated solution yields Fe particles of smallest size with a superp aramagnetic doublet in the Mossbauer spectrum arising from oxide nanopartic les; (2) moderately diluted solution yields Fe particles of maximum size, a nd the Mossbauer spectrum was a superposition of a sextet line arising from Fe3O4, a superparamagnetic singlet, and doublet from Fe and its oxides; (3 ) fairly diluted solution yields Fe particles of intermediate size and the Mossbauer spectrum was a superposition of a sextet line corresponding to me tallic alpha -Fe and superparamagnetic line similar to case (2). The experi mental results are discussed in terms of consecutive processes in the elect rochemical reaction. (C) 2001 Elsevier Science B.V. All rights reserved.