Layered Aluminum for Electromagnetic Wave Absorber with Near-Zero Reflection

Area of Science:

• Materials Science
• Electromagnetism
• Nanotechnology

Background:

• Ideal electromagnetic (EM) wave absorbers are crucial for various applications, but achieving high absorption with low reflection is challenging due to material properties.
• Electrical conductivity strongly influences absorptance and reflectance, making perfect absorption difficult to attain.

Purpose of the Study:

• To design a nearly ideal EM absorber with maximized absorption and minimized reflection.
• To develop a novel fabrication strategy for impedance-graded metallic materials.

Main Methods:

• A design strategy based on layered metal with monotonic gradient of intrinsic impedance was proposed.
• Aluminum nanoflakes were synthesized via topochemical etching of Li₉Al₄.
• Size-based sorting during dispersion was used to create the impedance-graded structure.

Main Results:

• A 120 μm thick film demonstrated strong EM wave absorption (26.76 dB) and negligible reflectivity (0.04 dB).
• The ratio of absorption to reflection exceeded 10³.
• The fabricated material exhibited properties close to an ideal EM absorber.

Conclusions:

• The proposed design strategy enables the creation of highly efficient EM wave absorbers.
• The findings suggest potential for developing novel antireflective shielding materials.
• This work offers a new approach to controlling EM wave interactions with materials.