Effects of composition on the microwave absorbing properties of FexNi100-x (x=0-25) submicro fibers

The morphology and composition of a material have important influences on its electromagnetic parameters and microwave absorbing property. In this paper, the FexNi100-x (x = 0-40) powders were prepared by an oxalate precipitation-thermal decomposition process. When x = 0-25, the powders show submicro fibrous morphologies, however, when x > 25, some granular particles appear due to the weak coordination ability of ethylenediamine with Fe2+ in the oxalate precipitation process. The electromagnetic parameters and microwave absorbing properties of the composites of the FexNi100-x (x = 0-25) submicro fibers with 80 wt% paraffin were studied in 2-18 GHz. Compared with the Ni/paraffin composite, enhanced electromagnetic losses and microwave absorbing properties are observed for the Fe10Ni90/paraffin and Fe25Ni75/paraffin composites. The Fe10Ni90/paraffin shows the best microwave absorbing property that at the composite thickness of 2.0 mm, the effective bandwidth and minimum RL reach 3.78 GHz (12.21-15.99 GHz) and -45.37 dB at 13.90 GHz, respectively. The excellent microwave absorbing property of the Fe10Ni90/paraffin composite is from its high loss factor and the quarter-wavelength cancellation mechanism. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.