Electron microscopy characterization of iron oxide nanopowders (prepared by Laser pyrolysis) for magnetic fluid applications

摘要

Fluids with magnetic characteristics have important values for today applications. This fluids, so called ferrofluids or magnetic fluids are in general formed by small nanoparticles with mean diameters about 10 nm and a carrier liquid. In our work we present nanopowders obtained by laser pyrolysis, which have characteristics for magnetic fluids applications. The important feature of powder was determined by means of XRD and electron microscopy techniques. The nanopowders have sizes distributed in interval from 2 nm to 10 nm. The high resolution images exhibits single particles with magnetic monodomain. Also, we investigate nanoparticles for defects. The nanoparticles forms nanoclusters, and high resolution image show adjacent particles without interface, the coupling mode is only magnetic not chemical. The powders are composed by magnetite and maghemite phase determined from XRD data, and confirmed by SAED and HRTEM work. The cell parameter calculated from the (220), (311), (511) (440) peaks of sample SF32 is 0.835 nm equal to the maghemite cell parameter.