Hexaferrite–FeCo nanocomposite particles and their electrical and magnetic properties at high frequencies

Sudakar, C and Subbanna, GN and Kutty, TRN (2003) Hexaferrite–FeCo nanocomposite particles and their electrical and magnetic properties at high frequencies. In: Journal of Applied Physics, 94 (9). pp. 6030-6033.

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Abstract

Nanocomposites are realized by chemical reduction whereby the conducting magnetic particles of Fe–Co alloy are generated within the insulating ferrimagnetic $BaCo_2Fe_{16}O_{27}$ or $Ba_2Co_2Fe_{12}O_{22}$ hexaferrite matrix. Transmission electron microscopy revealed that metal nanoparticles precipitate coherently as thin flakes along the a–b planes of the derivative magnetoplumbite lattice of the hexaferrites above the characteristic reduction temperature, $T_R$ >375 °C in $H_2$ atmosphere. The coercivity increases with $T_R$ in the early stages of the solid-state precipitation and then decreases with the formation of larger fractions of Fe–Co alloy; a converse trend is noticed for magnetization. The complex permittivity increases with reduction to ~50 in the broad frequency range of 4–18 GHz. The complex permeability is also enhanced with the content of Fe–Co nanoparticles. It is proposed that the spin reorientation at the Fe–Co/hexaferrite interface gives rise to broadband response, rendering these composite particles useful as electromagnetic microwave absorbers.

Item Type:	Journal Article
Publication:	Journal of Applied Physics
Publisher:	American Institute of Physics
Additional Information:	Copyright for this article belongs to American Institute of Physics (AIP).
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	04 May 2006
Last Modified:	19 Sep 2010 04:17
URI:	http://eprints.iisc.ac.in/id/eprint/2243

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