Gigahertz range electromagnetic wave absorbers made of amorphous-carbon-based magnetic nanocomposites
- Center for Advanced Science and Innovation, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)
Nanocomposite magnetic materials {alpha}-Fe/C(a), Fe{sub 2}B/C(a), and Fe{sub 1.4}Co{sub 0.6}B/C(a) were prepared by mechanically grinding {alpha}-Fe, Fe{sub 2}B, or Fe{sub 1.4}Co{sub 0.6}B with amorphous carbon [C(a)] powders. Complex permittivity, permeability, and electromagnetic wave absorption properties of resin compacts containing 40-vol % composite powders of {alpha}-Fe/C(a), Fe{sub 2}B/C(a), and Fe{sub 1.4}Co{sub 0.6}B/C(a) were characterized according to a conventional reflection/transmission technique. The real part ({epsilon}{sub r}{sup '}) and imaginary part ({epsilon}{sub r}{sup ''}) of the relative permittivity are low and almost independent of frequency between 0.05 and 40 GHz. The Imaginary part ({mu}{sub r}{sup ''}) of the relative permeability exhibited wide peaks in the 1-9-GHz range for {alpha}-Fe/C(a), in the 2-18-GHz range for Fe{sub 2}B/C(a), and in the 18-40-GHz range for Fe{sub 1.4}Co{sub 0.6}B/C(a) owing to their different magnetocrystalline anisotropy field (H{sub A}) values. Consequently, the resin compacts of 40-vol % {alpha}-Fe/C(a), Fe{sub 2}B/C(a), and Fe{sub 1.4}Co{sub 0.6}B/C(a) powders provided good electromagnetic (em) wave absorption performances (reflection loss<-20 dB) in ranges of 4.3-8.2 GHz (G band), 7.5-16.0 GHz (X band), and 26.5-40 GHz (Q band) over absorber thicknesses of 1.8-3.3, 1.2-2.2, and 0.63-0.82 mm, respectively. Our experimental results demonstrate that the amorphous-carbon-based magnetic nanocomposites are promising for the application to produce thin and light EM wave absorbers.
- OSTI ID:
- 20714092
- Journal Information:
- Journal of Applied Physics, Vol. 98, Issue 5; Other Information: DOI: 10.1063/1.2009082; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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