Journal
JOURNAL OF ADVANCED CERAMICS
Volume 10, Issue 1, Pages 62-77Publisher
SPRINGER
DOI: 10.1007/s40145-020-0417-2
Keywords
high entropy rare earth hexaborides (HE REB6); one-step synthesis; electromagnetic wave absorbing properties; synergistic dielectric and magnetic losses; wide effective absorption bandwidth
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Funding
- National Natural Science Foundation of China [51972089, 51672064, U1435206]
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The successful design and synthesis of high entropy rare earth hexaborides with coupling of dielectric and magnetic losses have potential for being promising new types of electromagnetic wave absorbing materials, showcasing excellent absorption properties among other hexaborides.
Considering the emergence of severe electromagnetic interference problems, it is vital to develop electromagnetic (EM) wave absorbing materials with high dielectric, magnetic loss and optimized impedance matching. However, realizing the synergistic dielectric and magnetic losses in a single phase material is still a challenge. Herein, high entropy (HE) rare earth hexaborides (REB6) powders with coupling of dielectric and magnetic losses were designed and successfully synthesized through a facial one-step boron carbide reduction method, and the effects of high entropy borates intermedia phases on the EM wave absorption properties were investigated. Five HE REB(6)ceramics including (Ce0.2Y0.2Sm0.2Er0.2Yb0.2)B-6, (Ce0.2Eu0.2Sm0.2Er0.2Yb0.2)B-6, (Ce0.2Y0.2Eu0.2Er0.2Yb0.2)B-6, (Ce0.2Y0.2Sm0.2Eu0.2Yb0.2)B-6, and (Nd0.2Y0.2Sm0.2Eu0.2Yb0.2)B(6)possess CsCl-type cubic crystal structure, and their theoretical densities range from 4.84 to 5.25 g/cm(3). (Ce0.2Y0.2Sm0.2Er0.2Yb0.2)B(6)powders with the average particle size of 1.86 mu m were found to possess the best EM wave absorption properties among these hexaborides. TheRL(min)value of (Ce0.2Y0.2Sm0.2Er0.2Yb0.2)B(6)reaches -33.4 dB at 11.5 GHz at thickness of 2 mm; meanwhile, the optimized effective absorption bandwidth (E-AB) is 3.9 GHz from 13.6 to 17.5 GHz with a thickness of 1.5 mm. The introduction of HE REBO3(RE = Ce, Y, Sm, Eu, Er, Yb) as intermediate phase will give rise to the mismatching impedance, which will further lead to the reduction of reflection loss. Intriguingly, the HEREB6/HEREBO(3)still possess wide effective absorption bandwidth of 4.1 GHz with the relative low thickness of 1.7 mm. Considering the better stability, low density, and good EM wave absorption properties, HE REB(6)ceramics are promising as a new type of EM wave absorbing materials.
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