Síntese e caracterização da hexaferrita de bário tipo m dopada com lantânio e sódio para utilização como absorvedor de microondas

Abstract

ResumoHexaferrita de Bário, dopada com lantânio e sódio, foi obtida pelo processo de mistura de óxidos. A composição utilizada foi Ba 0,8 La 0,1 Na 0,1 Fe 12 O 19 . Este trabalho teve como objetivo reduzir o valor da freqüência de ressonância da hexaferrita de bário tipo M de modo que a mesma possa absorver microondas na faixa de freqüência de 8 a 16 GHz. Para se investigar a fase obtida, o material foi submetido a difração de raios X. A morfologia das partículas foi verificada pela técnica de microscopia eletrônica de varredura. Suas propriedades magnéticas e de absorção de microondas foram estudadas utilizando-se o magnetômetro de amostra vibrante e guia de ondas, respectivamente. Palavras-chave: hexaferrita de bário, absorvedor de microondas, mistura de óxidos. Abstract Lanthanum and sodium doped barium hexaferrite was obtained by the mixed-oxide technique. The composition was Ba

Influence of calcination temperature on the morphology and magnetic properties of Ni–Zn ferrite applied as an electromagnetic energy absorber

“…On the other hand, although the ferrite calcined at 800 and 1000 • C presented a lower reflectivity value of around −3 dB, it showed a wide band electromagnetic radiation absorption behavior, i.e., the reflectivity value remained practically unaltered in the frequency range of 8-12 GHz. A comparison of these results against those reported by Lima et al [9] for hexaferrites obtained by the oxide mixing process indicates a similar resonance behavior resulting in the increase of resonance frequency from −4 to −7 dB, indicating that this material is suitable for use as a narrow band electromagnetic radiation absorber. …”

Correlation between coercive field and radiation attenuation in Ni and Mg ferrite doped with Mn and Co

“…There has been a great challenge to rationalize the processing technology of radar absorbing materials, RAM, [1,2,3,4]. Successful usages of these materials are: in aeronautics with the aim of reducing the detection of a target by a radar; in telecommunications, where the magnetic nuclei are used to eliminate the microwave band radiation in large scale equipment; in electronics, where the cabling systems that reduce or eliminate spurious radiation caused by electronic gadgets; in army, for the intelligent monitoring of camouflage; in medicine, for the radiation shielding of medical equipment.…”