Resumo

CAFFARENA, V. R.; OGASAWARA, T.; CAPITANEO, J. L.  e  SILVEIRA PINHO, M.. Microwave absorptive behavior ofnanocrystalline Ba₃Co_1.3Zn_0.3Cu_0.4Fe₂₄O₄₁ powder. Lat. Am. appl. res. [online]. 2008, vol.38, n.3, pp.235-239. ISSN 0327-0793.

In the present work, Cu²⁺ and Zn²⁺ ions were incorporated into the structure of Ba₃Co₂Fe₂₄O₄₁, in order to obtain the Ba₃Co_1.3Zn_0.3Cu_0.4Fe₂₄O₄₁ structure, by the sol-gel precursor method in N₂ inert atmosphere. The magnetization curves of Ba₃Co_1.3Zn_0.3Cu_0.4Fe₂₄O₄₁ hexaferrite nanopowders were analyzed as a function of temperature, to evaluate the super-paramagnetic (SPM) behavior and its effect on the microwave absorption measurements. The permittivity (ε) and permeability (μ) values were obtained by using the transmission/reflection (T/R) method in a waveguide to evaluate the microwave absorption properties at S and X-Ku bands, for radar absorber material (RAM) application. The partial substitu-tion of Co for Zn and Cu ions and the superpara-magnetic contribution improved the ceramics´ magnetic permeability, resulting in a microwave absorption greater than 90.0 % (reflectivity ≤ -10 dB) at 10.0-12.5 GHz and 13.0-16.0 GHz, with 2.5 and 2.0 mm thick, respectively.

Palavras-chave : Z-Type Hexaferrite; RAM; Magnetic Properties; Sol-Gel Synthesis.

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