Functionally Graded Tunable Microwave Absorber with Graphene-Augmented Alumina Nanofibers

Ali Saffar Shamshirgar, Rocio E. Rojas Hernandez, Girish C. Tewari, Jose Francisco Fernandez, Roman Ivanov, Maarit Karppinen, Irina Hussainova*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

5 Citations (Scopus)


Graphene is currently attracting attention for radiation absorption particularly at gigahertz and terahertz frequencies. In this work, composites formed by graphene-augmented γ-Al2O3 nanofibers embedded into the α-Al2O3 matrix are tested for X-band absorption efficiency. Composites with 15 and 25 wt % of graphene fillers with shielding effectiveness (SE) of 38 and 45 dB, respectively, show a high reflection coefficient, while around the electrical percolation threshold (∼1 wt %), an SE of 10 dB was achieved. Furthermore, based on the dielectric data obtained for varying fractions of graphene-/γ-Al2O3-added fillers, a functionally graded multilayer is constructed to maximize the device efficiency. The fabricated multilayer offers the highest absorption efficiency of 99.99% at ∼9.6 GHz and a full X-band absorption of >90% employing five lossy layers of 1-3-5-15 and 25 wt % of graphene/γ-Al2O3 fillers. The results prove a remarkable potential of the fillers and various multilayer designs for broad-band and frequency-specific microwave absorbers.

Original languageEnglish
Pages (from-to)21613–21625
Number of pages13
JournalACS Applied Materials and Interfaces
Issue number18
Early online date27 Apr 2021
Publication statusPublished - 12 May 2021
MoE publication typeA1 Journal article-refereed


  • alumina
  • graphene
  • hybrid nanofibers
  • impedance matching
  • microwave absorption
  • multilayer structure


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