Nanoparticles are of immense importance both from the fundamental and
application points of view. They exhibit quantum size effects which are
manifested in their improved magnetic and electric properties. Mechanical
attrition by high energy ball milling (HEBM) is a top down process for
producing fine particles. However, fineness is associated with high surface
area and hence is prone to oxidation which has a detrimental effect on the
useful properties of these materials. Passivation of nanoparticles is known to
inhibit surface oxidation. At the same time, coating polymer film on
inorganic materials modifies the surface properties drastically. In this work a
modified set-up consisting of an RF plasma polymerization technique is
employed to coat a thin layer of a polymer film on Fe nanoparticles produced
by HEBM. Ball-milled particles having different particle size ranges are
coated with polyaniline. Their electrical properties are investigated by
measuring the dc conductivity in the temperature range 10–300 K. The low
temperature dc conductivity (I–V ) exhibited nonlinearity. This nonlinearity
observed is explained on the basis of the critical path model. There is
clear-cut evidence for the occurrence of intergranular tunnelling. The results
are presented here in this paperCochin University of Science and TechnologyNanotechnology 17 (2006) 4765–477