Key Takeaways & Executive Findings
- •• Bi-phase high-entropy composites (BPHEC) with FeCoNiCr0.4Cu0.2 alloy and (FeCoNiCrCu)3O4 oxide are fabricated via low-temperature oxygen bath, enabling precise electromagnetic gene regulation. • The BPHEC achieves ultra-broadband absorption (633 MHz at 5 mm thickness) and a minimum reflection loss of −12.8 dB, with RCS reduction up to 18.34 dB m2 in multilayer designs. • Temperature-stable absorption (593–691 MHz) from −50 to 150 °C, along with high Curie temperature and oxidation resistance, ensures environmental adaptability. • The study elucidates formation and regulation mechanisms, offering a tunable strategy for low-frequency EMW absorption materials.
Abstract
Magnetic absorbers with high permeability have significant advantages in low-frequency and broadband electromagnetic wave (EMW) absorption. However, the insufficient magnetic loss and inherent high conductivity of existing magnetic absorbers limit the further expansion of EMW absorption bandwidth. Herein, the spinel (FeCoNiCrCu)3O4 high-entropy oxides (HEO) are successfully constructed on the surface of FeCoNiCr0.4Cu0.2 high-entropy alloys (HEA) through low-temperature oxygen bath treatment. On the one hand, HEO and HEA have different magnetocrystalline anisotropies, which is conducive to achieving continuous natural resonance to improve magnetic loss. On the other hand, HEO with low conductivity can serve as an impedance matching layer, achieving magneto-electric co-modulation. When the thickness is 5 mm, the minimum reflection loss (RL) value and absorption bandwidth (RL < −5 dB) of bi-phase high-entropy composites (BPHEC) can reach −12.8 dB and 633 MHz, respectively. The RCS reduction value of multilayer sample with impedance gradient characteristic can reach 18.34 dB m2. In addition, the BPHEC also exhibits temperature-stable EMW absorption performance, high Curie temperature, and oxidation resistance. The absorption bandwidth maintains between 593 and 691 MHz from −50 to 150 °C. This work offers a new and tunable strategy toward modulating the electromagnetic genes for temperature-stable ultra-broadband megahertz EMW absorption.
1. Introduction
Low-frequency electromagnetic wave (EMW) absorption materials have wide applications in both civil and military fields, and it is of great significance to strengthen the research of EMW absorption materials in the megahertz (MHz) frequency band [1–5]. As the frequency decreases, the coupling degree between wave-impedance and EMW dissipating ability significantly increases, which puts higher requirements on the electromagnetic parameters of EMW absorption materials [2]. The previous studies have shown that magnetic absorbers with high permeability exhibit strong advantages in low-frequency and broadband EMW absorption [6, 7]. In addition, the complex and variable application environments such as polar region, ocean, and desert put forward higher requirements for the environmental adaptability of EMW absorption materials [8–12].
High-entropy alloys (HEA) are considered to be suitable candidates for low-frequency broadband EMW absorption materials with environmental adaptability due to their high designable freedom in composition, microstructure, and morphology [13, 14]. The flake-shaped FeCoNi-based HEA absorbers prepared by a simple mechanical alloying method exhibit high permeability and strong low-frequency EMW absorption performance [15–17]. Meanwhile, due to the four effects of “high-entropy effect,” “cocktail effect,” “severe lattice distortion effect,” and “sluggish diffusion effect,” the FeCoNi-based HEA absorbers exhibit temperature-stable crystalline structure, high Curie temperature, excellent oxidation resistance, and corrosion resistance [9, 18–20]. However, on the one hand, the insufficient magnetic loss of existing HEA absorbers limits the realization of ideal MHz broadband EMW absorption. On the other hand, impedance mismatch due to the inherent high conductivity of metals can also limit the improvement of EMW absorption performance.
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Xiaoji Liu, Yuping Duan, Nan Wu, Guangming Li, Yuan Guo, Jiangyong Liu, Ning Zhu, Qiang Wang, Lin Wang, Zichen Xu, Hao Wei, Guojun Wang, Zhijia Zhang, Songsong Zhang, Wenjun Zhou, Teng Ma, Tongmin Wang (2025). Modulating Electromagnetic Genes Through Bi-Phase High-Entropy Engineering Toward Temperature-Stable Ultra-Broadband Megahertz Electromagnetic Wave Absorption. Nano-Micro Letters. https://doi.org/10.1007/s40820-024-01638-4
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Frequently Asked Questions
What are bi-phase high-entropy composites (BPHEC) and how are they synthesized?
BPHEC consist of FeCoNiCr0.4Cu0.2 high-entropy alloy (HEA) and (FeCoNiCrCu)3O4 high-entropy oxide (HEO) phases, synthesized via a low-temperature oxygen bath treatment. This method constructs HEO on the HEA surface, enabling precise electromagnetic gene modulation.
What electromagnetic wave absorption performance does BPHEC achieve?
At a thickness of 5 mm, BPHEC achieves a minimum reflection loss of −12.8 dB and an absorption bandwidth (RL < −5 dB) of 633 MHz. Multilayer samples with impedance gradient show RCS reduction up to 18.34 dB m2.
How does BPHEC maintain temperature-stable absorption?
BPHEC exhibits stable absorption bandwidth between 593 and 691 MHz across temperatures from −50 to 150 °C, attributed to high Curie temperature and oxidation resistance, ensuring performance in harsh environments.
What is the significance of 'electromagnetic genes' in this context?
Electromagnetic genes refer to the intrinsic electromagnetic parameters (permeability, permittivity) that determine absorption performance. BPHEC allows precise regulation of these genes through bi-phase engineering, optimizing impedance matching and magnetic loss.
What are the potential applications of this material?
The material is suitable for low-frequency EMW absorption in civil and military applications, including radar stealth, electromagnetic interference shielding, and devices requiring temperature stability in polar, oceanic, or desert environments.
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