A Novel Nano-Laminated GdB₂C₂ with Excellent Electromagnetic Wave Absorption Performance and Ultra-High-Temperature...

A novel nano-laminated GdB₂C₂ material was successfully synthesized using GdH₂, B₄C, and C via an in situ solid-state reaction approach for the first time. The formation process of GdB₂C₂ was revealed based on the microstructure and phase evolution investigation. Purity of 96.4 wt.% GdB₂C₂ was obtained at a low temperature of 1500 °C, while a nearly fully pure GdB₂C₂ could be obtained at a temperature over 1700 °C. The as-obtained GdB₂C₂ presented excellent thermal stability at a high temperature of 2100 °C in Ar atmosphere due to the stable framework formed by the high-covalence four-member and eight-member B-C rings in GdB₂C₂. The GdB₂C₂ material synthesized at 1500 °C demonstrated a remarkably low minimum reflection loss (RL_min) of -47.01 dB (3.44 mm) and a broad effective absorption bandwidth (EAB) of 1.76 GHz. The possible electromagnetic wave absorption (EMWA) mechanism could be ascribed to the nano-laminated structure and appropriate electrical conductivity, which facilitated good impedance matching, remarkable conduction loss, and interfacial polarization, along with the reflection and scattering of electromagnetic waves at multiple interfaces. The GdB₂C₂, with excellent EMWA performance as well as remarkable ultra-high-temperature thermal stability, could be a promising candidate for the application of EMWA materials in extreme ultra-high temperatures.