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In this study, a chloride-assisted boro/carbothermal reduction method was employed to prepare HfB 2 whiskers, aiming to address the challenges associated with large-scale preparation of HfB 2 whiskers and the development of high-temperature resistant electromagnetic wave absorbing materials. When the precursors were mechanically stirred, the resulting mixture underwent calcination at 1450 °C for 3 h, leading to the formation of single-phase HfB 2 whiskers. The as-synthesized HfB 2 whiskers showed exceptional resistance to oxidation at temperatures up to 700 °C. The microwave absorption performance and mechanism of the HfB 2 whiskers/paraffin composite were also investigated. The results revealed that the composite achieved a minimum reflection loss of −41.29 dB when the HfB 2 whiskers content reached 80 wt%, while the widest effective absorption bandwidth of the composite reached 3.6 GHz when the HfB 2 whiskers content increased to 82.5 wt%. This work presents a novel candidate for high-temperature resistant materials used in absorbing electromagnetic wave. [ABSTRACT FROM AUTHOR]

In this study, a chloride-assisted boro/carbothermal reduction method was employed to prepare HfB 2 whiskers, aiming to address the challenges associated with large-scale preparation of HfB 2 whiskers and the development of high-temperature resistant electromagnetic wave absorbing materials. When the precursors were mechanically stirred, the resulting mixture underwent calcination at 1450 °C for 3 h, leading to the formation of single-phase HfB 2 whiskers. The as-synthesized HfB 2 whiskers showed exceptional resistance to oxidation at temperatures up to 700 °C. The microwave absorption performance and mechanism of the HfB 2 whiskers/paraffin composite were also investigated. The results revealed that the composite achieved a minimum reflection loss of −41.29 dB when the HfB 2 whiskers content reached 80 wt%, while the widest effective absorption bandwidth of the composite reached 3.6 GHz when the HfB 2 whiskers content increased to 82.5 wt%. This work presents a novel candidate for high-temperature resistant materials used in absorbing electromagnetic wave. [ABSTRACT FROM AUTHOR]

Nowadays, the increasingly severe electromagnetic (EM) wave pollution requires high-performance EM wave absorbing materials. Multi-principal-element materials are acknowledged as promising for broadening the applications owing to their tunable chemistries and structures in many fields, including as EM wave absorbers. Herein, we prepared a high-entropy MXene, (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25) 3 C 2 T x. Furthermore, multi-principal-element (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25) 3 C 2 T x /FeCoNi and (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25) 3 C 2 T x /FeCoNiCu composites were synthesized via an in-situ hydrothermal process by combining high-entropy MXene with medium-entropy magnetic alloys. In contrast with the relatively narrow effective absorption bandwidth (EAB) of (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25) 3 C 2 T x MXene (2.56 GHz), (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25) 3 C 2 T x /FeCoNi composite with 50 wt% MXene can attain an optimum EAB of 4.88 GHz with the matching thickness of only 1.73 mm. As for (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25) 3 C 2 T x /FeCoNiCu composites, both the absorption efficiency and absorption bandwidth are significantly enhanced. The combination of multi-principal-component strategy and composite construction endows the composites with synergistic dielectric and magnetic losses, optimized impedance matching as well as enhanced attenuation ability, thus improving EM wave absorption performances. In addition, radar cross section (RCS) simulation confirms that the prepared composites have broad application prospects as radar stealth materials. [ABSTRACT FROM AUTHOR]

The TiB 2 fibers were prepared by a chloride-assisted carbothermic method accompanied with the vapor-liquid-solid (VLS) mechanism. The influences of TiO 2 , B 2 O 3 , C 12 H 22 O 11 , and calcination temperature on the yield of TiB 2 fibers were investigated. In addition, the effects of TiB 2 fibers content on the electromagnetic (EM) parameters and microwave absorption (MA) properties of TiB 2 fibers/paraffin composite was studied in detail. The TiB 2 fibers/paraffin composite showed excellent microwave absorption performance, with an optimized reflection loss (RL) of −46.63 dB at 14 GHz and a thickness of 1.5 mm. Moreover, it exhibited a broad effective absorption bandwidth (EAB) (RL < −10 dB) of 3.9 GHz, ranging from 12 to 15.9 GHz. TiB 2 fibers exhibit promising potential as materials for high-temperature applications in the field of MA. [ABSTRACT FROM AUTHOR]