Preparation of CoFe alloy nanoparticles with tunable electromagnetic wave absorption performance

CoFe alloy nanoparticles with different particle sizes were successfully prepared by hydrogen-thermal reduction of CoFe2O4 microspheres at different temperatures. It was found that the real part of the permeability of the CoFe alloy nanoparticles increased with the decrease of the particle size, and accordingly the reflection loss (RL) peak moved towards the low-frequency region. The maximum RL of the coating based on CoFe alloy nanoparticles exceeded -23 dB, and a wide effective absorption band width (RLr <=-10dB) of about 6 GHz was simultaneously achieved. The EMA performance was confirmed to be tunable by the control of the absorber's particle size, and thus a new clue for the design of the EMA applications was supplied. (C) 2009 Elsevier B.V. All rights reserved.