Advanced Multilayer FeNi3@C Composite for Ultra-Broad Microwave Absorption

What is it about?

This research describes the development of a new type of material designed to absorb microwave radiation effectively. The material is made of tiny magnetic particles called FeNi3, which are coated with multiple layers of porous carbon, forming a core–shell structure. This layered design creates many interfaces and defects that help generate polarization, a process where electric charges accumulate at boundaries, effectively dissipating microwave energy. The composite’s unique multilayer carbon shell boosts the material’s ability to generate multiple types of polarization – especially interfacial polarization, which occurs at the boundaries between different materials, and dipole polarization, caused by defects in the carbon shell. These mechanisms improve how well the material can convert microwave energy into heat, making it an excellent absorber. The complex structure allows the material to absorb a wide range of frequencies, from as low as 2 GHz to as high as 18 GHz, while remaining very thin. This broad absorption range is achieved through careful designing of the microstructure, including layered coatings that cause multiple reflections and scattering of microwaves inside the material. It also enhances impedance matching, meaning the material allows microwaves to enter smoothly without bouncing off, which improves absorption efficiency. Compared to existing materials, this composite addresses the challenge of balancing broadband absorption and thinness, which are typically difficult to achieve together. The study demonstrates that the multilayer FeNi3@C is promising for practical applications like stealth technology and electromagnetic interference shielding, where lightweight, compact, and efficient absorbent materials are required.

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Photo by Jan Antonin Kolar on Unsplash

Photo by Jan Antonin Kolar on Unsplash

Why is it important?

As electromagnetic pollution from communication devices, radar, and other equipment continues to grow, there is an urgent need for materials that can block or weaken microwave radiation effectively. Such materials are essential in military applications like stealth technology, which helps military equipment avoid detection, and in safeguarding electronic devices from interference that can cause malfunctions. Traditional microwave absorbers often suffer from limitations like narrow frequency ranges, significant thickness, or complex manufacturing processes. This research offers a breakthrough by creating a material that can absorb a wide range of microwave frequencies while remaining very thin and lightweight. The core–shell design with multilevel carbon layers enhances multiple loss mechanisms—such as dielectric loss, magnetic loss, and interfacial polarization—allowing the material to dissipate electromagnetic energy efficiently. The layered structure promotes polarization processes and multiple scattering of microwaves inside the material, increasing absorption without making it bulkier. This approach also effectively prevents the clumping of magnetic particles, which can reduce absorption performance. Developing such advanced materials is crucial not only for stealth technology, where minimizing detectability is vital, but also for shielding sensitive electronic systems from electromagnetic interference that can damage or disrupt operations. The ability to produce broadband, high-performance absorbers that are thin and easy to manufacture will open new opportunities in military, civilian, and industrial sectors, contributing to safer, more secure, and more reliable electronic systems worldwide. Key takeaways: • The multilayer FeNi3@C composite efficiently absorbs a wide range of microwave frequencies from 2 to 18 GHz. • The layered carbon shell enhances interfacial polarization and scattering, boosting microwave energy dissipation. • The design addresses challenges of making thin, lightweight materials that perform broadband microwave absorption. • The structured composite improves impedance matching, allowing microwaves to enter easily and be absorbed. • This research provides a promising material for stealth, electromagnetic shielding, and electronic protection.