Advances in Fe-based electromagnetic wave absorbers: Multiscale engineering from atomic defects to macroscopic architectures for performance optimization

Abstract

The rapid development of electronic devices and communication technologies has resulted in increasingly severe electromagnetic-wave (EW) pollution. Efficient EW absorption (EWA) materials are essential to mitigate their impact and ensure human safety in modern society. Fe-based EWA materials have garnered significant attention owing to their cost-effectiveness, high saturation magnetization, and superior magnetic loss capabilities. This review begins with an introduction to Fe-based EWA materials, followed by a brief description of their EWA mechanisms. Various pristine Fe-based absorbers, such as carbonyl iron powder, ferrite-based materials, Fe-based alloys, Fe-based high-entropy alloys (HEAs), and Fe-based layered ternary transition-metal borides, have been systematically reviewed. Key strategies to enhance the performance of Fe-based composite absorbers, including doping, in-situ oxidation, porous structuring, and composite construction, are critically discussed. Finally, the review presents a summary and future perspectives in this field, highlighting the synergy between Fe-based and high-entropy materials in advancing next-generation EWA for applications in stealth technology, wearable electronics, and harsh environments.

1. Introduction

With the widespread use of electronic devices, humans are increasingly exposed to electromagnetic waves (EWs) [1–5]. Prolonged exposure to EWs can lead not only to thermal effects but also to controversial health concerns such as neurological discomfort and sleep disturbances [6–9]. Given the indispensable role of these devices in modern society, the development of efficient EW absorption (EWA) materials is crucial for mitigating EW pollution and safeguarding human health. Ideal EWA materials should exhibit minimal thickness, lightweight, broad absorption bandwidth, and high absorption efficiency, collectively known as the “thin, lightweight, wide, and strong” criteria [10–13].

Among various EWA, Fe-based EWA materials, a class of functional materials with Fe or its compounds as core components, are renowned for their exceptional EW absorption capabilities [14–15]. They are widely used in military stealth technology [16–18], electromagnetic shielding for electronic devices [19–22], and anti-interference communication systems [23].

The advantages of Fe-based EWA materials include [24–25]: (1) High magnetic permeability and significant dielectric loss. Fe-based materials such as ferrites, Fe nanoparticles, and Fe-based alloys can effectively convert EW energy into heat, particularly in the GHz frequency range. This conversion occurs through hysteresis loss, eddy current loss, and natural resonance, which together transform incident EWs to thermal energy, thereby minimizing reflection and transmission. For instance, ferrites exhibit strong absorption in the mid-to-high-frequency range owing to the magnetic domain motion within their crystalline structure. Their absorption performance can be further enhanced by doping, which optimizes impedance matching. (2) Design flexibility and adaptability. Fe-based materials form composites with other materials (e.g., carbon-based materials, polymers, and ceramics) to create heterogeneous microstructures that leverage synergistic effects to optimize electromagnetic parameters, broaden absorption bandwidths, and reduce material thickness [26–28]. For example, Fe nanoparticle–graphene hybrids combine the high conductivity of graphene, which enhances dielectric loss, with the magnetic loss properties of Fe. This synergy addresses the weak magnetic performance of pure carbon materials and achieves broadband absorption. (3) Environmental stability. Because of their inherent resistance to thermal degradation, corrosion, and mechanical stress, Fe-based materials demonstrate superior stability under harsh conditions, making them well-suited for field deployment. For instance, FeSiAl alloys maintain stable EWA properties at high temperatures, which are ideal for aerospace applications. (4) Cost-effectiveness and scalability. Fe-based EWA materials can be fabricated from inexpensive raw materials using mature synthesis techniques, such as hydrothermal synthesis, sol–gel methods, and mechanical alloying. These techniques allow precise control over microstructures (e.g., flake-like, spherical, or core–shell morphologies) to optimize absorption efficiency [29]. Although Fe-based EWA materials are promising, their drawbacks cannot be overlooked. For example, Fe-based EWA materials generally have a relatively high density, which may limit their application in weight-sensitive scenarios. This issue can be effectively mitigated through porous structure designs or formi