TY - JOUR
T1 - Functionally Graded Tunable Microwave Absorber with Graphene-Augmented Alumina Nanofibers
AU - Shamshirgar, Ali Saffar
AU - Rojas Hernandez, Rocio E.
AU - Tewari, Girish C.
AU - Fernandez, Jose Francisco
AU - Ivanov, Roman
AU - Karppinen, Maarit
AU - Hussainova, Irina
N1 - Funding Information:
This research was supported by the Estonian Research Council under the personal grant PRG643 (I.H.). R.E. Rojas-Hernandez acknowledges the financial support of the Estonian Research Council (ETAG) through PSG 466. The authors would like to acknowledge the help of Dr. Olga Volobujeva from the Department of Materials and Environmental Technologies, TalTech, for SEM imaging. The RawMatTERS Finland infrastructure (RAMI) facilities based at Aalto University is acknowledged for low-temperature electronic transport measurements. The authors acknowledge the originality of all figures, including the TOC graphics.
Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/5/12
Y1 - 2021/5/12
N2 - 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.
AB - 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.
KW - alumina
KW - graphene
KW - hybrid nanofibers
KW - impedance matching
KW - microwave absorption
KW - multilayer structure
UR - http://www.scopus.com/inward/record.url?scp=85106479095&partnerID=8YFLogxK
U2 - 10.1021/acsami.1c02899
DO - 10.1021/acsami.1c02899
M3 - Article
C2 - 33905645
AN - SCOPUS:85106479095
VL - 13
SP - 21613
EP - 21625
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
SN - 1944-8244
IS - 18
ER -