Facile chemical synthesis, electromagnetic response, and enhanced microwave absorption of cobalt powders with controllable morphologies.

Spherical (sample A), chain-like (sample B), and flake-like (sample C) cobalt powders are synthesized on a large scale through simple chemical liquid reduction method. Based on uniformly dispersing samples into a paraffin matrix, morphology-dependent electromagnetic responses in GHz range, including permittivity and permeability, are investigated for these three cobalt powders in the microwave frequency of 2-18 GHz. The calculated reflection loss (RL) indicates as-prepared samples have potential application as a candidate for microwave absorption. The maximum RL of sample A is -15.28 dB at 12.85 GHz with a matching thickness of 2.5 mm. The maximum RL of sample B is -28.05 dB at 5.74 GHz corresponding to a thickness of 2.0 mm, and the maximum RL of sample C is -41.17 dB at 5.10 GHz with a thickness of 2.5 mm. Mechanism of morphology-dependent electromagnetic response and microwave absorption of the Cobalt powders is also discussed in this paper.