Rare-Earth-Sulfur Surface Modification Enables SiC Ceramics for Low-Frequency Electromagnetic Wave Absorption in...

Area of Science:

• Materials Science
• Nanotechnology
• Electromagnetics

Background:

• Developing stable low-frequency electromagnetic wave (EMW) absorbers for extreme environments is critical for radar stealth and anti-electromagnetic interference.
• Silicon carbide (SiC) ceramics are promising but require enhanced EMW absorption properties and environmental stability.

Purpose of the Study:

• To develop a surface modification strategy for SiC-based ceramics to enhance low-frequency EMW absorption.
• To improve the stability of EMW absorbers in extreme environmental conditions.
• To investigate the mechanism behind enhanced EMW absorption through surface chemical bond evolution.

Main Methods:

• Surface modification of SiC ceramics using rare-earth-sulfur (RE─S) compounds (RE = La, Ce, Pr, Sm, Gd, Er).
• Analysis of surface chemical bond evolution from Si─O to RE─O species.
• Characterization of electromagnetic response, including reflection loss (RL) and polarization relaxation time.
• Evaluation of thermal response, corrosion resistance, and oxidation stability.

Main Results:

• The RE─S surface modification effectively transformed fast-relaxation dipoles to slow-relaxation dipoles, shifting the absorption peak to the C band.
• Optimized SiC/Ce-S ceramics achieved a minimum RL of -60.08 dB at 5.76 GHz.
• The modified ceramics demonstrated broad universality across multiple RE elements and excellent stability, retaining RL of -54.46 dB after annealing at 500°C.

Conclusions:

• The RE─S surface modification strategy provides a viable route for designing multifunctional SiC-based EMW absorbers.
• Synergistic regulation of surface chemistry, dipole polarization, and dielectric relaxation enhances EMW absorption.
• The developed materials exhibit superior performance and stability for applications in extreme environments.