Single- and Double-Layer Microwave Absorbers of Cobalt Ferrite and Graphite Composite at Gigahertz Frequency

Ismayadi Ismail, Khamirul Amin Matori, Zulkifly Abbas, Muhamad Misbah Muhamad Zulkimi, Fadzidah Mohd Idris, Mohd Hafiz Mohd Zaid, Nurfaziera Rahim, Intan Helina Hasan, Hai Song Woon

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Microwave absorbers of cobalt ferrite and graphite composite have been fabricated to investigate the broadening of absorption frequency by mixing small and large particles and comparing single- and double-layer composites in order to broaden the absorption frequency and to enhance multireflection and scattering of electromagnetic wave. CoO and Fe2O3 precursors were mechanically alloyed and sintered at 800, 900, 1000 and 1100 C in order to synthesise various particle sizes and shapes. A mixed sample of powders sintered at the above mentioned temperatures was also formed. The morphological, phase, and magnetic properties of these samples were studied. Two series of samples have been synthesised which were single- and double-layer composites. Single-layer composite consisted of mixed particles, and their thickness parameters were varied. Double-layer composite was also prepared with various particle sizes of CoFe2O4 as a layer and graphene as another layer. The effect of these layers as matching and absorbing layer was studied. The degree of crystallinity of CoFe2O4 was increased with increase of sintering temperature. Microstructural study showed the evolution of particle size and shape subjected to sintering temperature. Arrhenius plot showed two stages of growth process with activation energy calculated at 26.85 and 83.091 kJ/mol. The critical size of single domain of this sample plotted from the coercivity against particle size was 63.44 nm. Single-layer composite with mixed particle size was not able to show good electromagnetic (EM)-wave absorption; however double-layer composite showed good return loss. The mechanism of the EM-wave absorption of double-layer composite was discussed in this paper.

Original languageEnglish
Pages (from-to)935-943
Number of pages9
JournalJournal of Superconductivity and Novel Magnetism
Volume32
Issue number4
DOIs
Publication statusPublished - 15 Apr 2019

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Graphite
Ferrite
ferrites
Cobalt
absorbers
cobalt
graphite
Microwaves
microwaves
composite materials
Composite materials
Particle size
Electromagnetic wave absorption
electromagnetic radiation
Sintering
Arrhenius plots
sintering
cobalt ferrite
Coercive force
Electromagnetic waves

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Ismail, Ismayadi ; Matori, Khamirul Amin ; Abbas, Zulkifly ; Zulkimi, Muhamad Misbah Muhamad ; Idris, Fadzidah Mohd ; Zaid, Mohd Hafiz Mohd ; Rahim, Nurfaziera ; Hasan, Intan Helina ; Woon, Hai Song. / Single- and Double-Layer Microwave Absorbers of Cobalt Ferrite and Graphite Composite at Gigahertz Frequency. In: Journal of Superconductivity and Novel Magnetism. 2019 ; Vol. 32, No. 4. pp. 935-943.
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Single- and Double-Layer Microwave Absorbers of Cobalt Ferrite and Graphite Composite at Gigahertz Frequency. / Ismail, Ismayadi; Matori, Khamirul Amin; Abbas, Zulkifly; Zulkimi, Muhamad Misbah Muhamad; Idris, Fadzidah Mohd; Zaid, Mohd Hafiz Mohd; Rahim, Nurfaziera; Hasan, Intan Helina; Woon, Hai Song.

In: Journal of Superconductivity and Novel Magnetism, Vol. 32, No. 4, 15.04.2019, p. 935-943.

Research output: Contribution to journalArticle

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AU - Ismail, Ismayadi

AU - Matori, Khamirul Amin

AU - Abbas, Zulkifly

AU - Zulkimi, Muhamad Misbah Muhamad

AU - Idris, Fadzidah Mohd

AU - Zaid, Mohd Hafiz Mohd

AU - Rahim, Nurfaziera

AU - Hasan, Intan Helina

AU - Woon, Hai Song

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AB - Microwave absorbers of cobalt ferrite and graphite composite have been fabricated to investigate the broadening of absorption frequency by mixing small and large particles and comparing single- and double-layer composites in order to broaden the absorption frequency and to enhance multireflection and scattering of electromagnetic wave. CoO and Fe2O3 precursors were mechanically alloyed and sintered at 800, 900, 1000 and 1100 ∘C in order to synthesise various particle sizes and shapes. A mixed sample of powders sintered at the above mentioned temperatures was also formed. The morphological, phase, and magnetic properties of these samples were studied. Two series of samples have been synthesised which were single- and double-layer composites. Single-layer composite consisted of mixed particles, and their thickness parameters were varied. Double-layer composite was also prepared with various particle sizes of CoFe2O4 as a layer and graphene as another layer. The effect of these layers as matching and absorbing layer was studied. The degree of crystallinity of CoFe2O4 was increased with increase of sintering temperature. Microstructural study showed the evolution of particle size and shape subjected to sintering temperature. Arrhenius plot showed two stages of growth process with activation energy calculated at 26.85 and 83.091 kJ/mol. The critical size of single domain of this sample plotted from the coercivity against particle size was 63.44 nm. Single-layer composite with mixed particle size was not able to show good electromagnetic (EM)-wave absorption; however double-layer composite showed good return loss. The mechanism of the EM-wave absorption of double-layer composite was discussed in this paper.

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