Electric Double-Layer Structured Grain Boundaries in Medium-Entropy Perovskite Enable Robust Electromagnetic...

Area of Science:

• Materials Science
• Ceramic Engineering
• Electromagnetics

Background:

• High-temperature electromagnetic interference (EMI) shielding materials are critical for aerospace, but stability above 1000°C is a significant challenge.
• Existing oxide ceramics often lack the required thermal stability and shielding efficiency for demanding aerospace applications.

Purpose of the Study:

• To develop novel oxide ceramics with enhanced high-temperature EMI shielding capabilities.
• To investigate the formation of electric double-layer (EDL) structured grain boundaries (GBs) via point defect segregation for improved material properties.

Main Methods:

• Utilized a highly deficient medium-entropy (ME) perovskite, (SrBaLa)1/3TiO3, known for high Ti and O vacancies.
• Sintered the perovskite to induce segregation of Ti and O vacancies at GBs, forming EDL structures.
• Characterized the complex permittivity, EMI shielding effectiveness, flexural strength, and hardness of the sintered ceramic.

Main Results:

• The sintered (SrBaLa)1/3TiO3 exhibited enhanced dipole polarization and higher complex permittivity compared to its powders.
• Achieved EMI shielding effectiveness exceeding 32 dB in the X-band, stable up to 1200°C in air.
• The ceramic demonstrated superior flexural strength (217.2 MPa) and hardness (11.6 GPa) due to vacancy clustering.

Conclusions:

• The proposed EDL structure at GBs effectively enhances EMI shielding performance and thermal stability in oxide ceramics.
• The developed (SrBaLa)1/3TiO3 ceramic is a mechanically robust and thermally stable material suitable for aerospace EMI shielding.
• This work validates a new protocol for fabricating advanced EMI shielding materials for extreme environments.