In Situ Grown 1D/2D Structure of Dy3Si2C2 on SiCw for Enhanced Electromagnetic Wave Absorption

Abstract Dysprosium (Dy)‐doped (Y1−xDyx)3Si2C2 (x = 0, 0.1, 0.3, 0.5) solid solution ceramics were successfully fabricated using an in situ reaction spark plasma sintering technology, for the first time. The effect of various Dy doping contents (x) on the microstructure, mechanical, and thermal properties of (Y1−xDyx)3Si2C2 ceramics was investigated. The (0 2 0) crystal plane spacing of (Y0.5Dy0.5)3Si2C2 was 7.813 Å, which was smaller than that of Y3Si2C2, due to the fact that the atomic radius of Dy is smaller than that of Y. The Dy doping facilitated the consolidation of (Y1−xDyx)3Si2C2, thus a highly dense (Y0.5Dy0.5)3Si2C2 ceramic material with a low open porosity of 0.14% was successfully obtained at a relatively low temperature of 1 200°C. As the content of Dy doping (x) increased from 0 to 0.5, the purity of (Y1−xDyx)3Si2C2 ceramics increased from 88.3 to 90.7 wt.%, while the grain size of (Y1−xDyx)3Si2C2 ceramics decreased from 0.59 to 0.46 µm. As a result, the Vickers hardness and thermal conductivity of the (Y0.5Dy0.5)3Si2C2 material was 7.1 GPa and 9.8 W·m−1·K−1, respectively.

Carbon-enriched PDC-SiC with enhanced electromagnetic wave absorption: A study examining the impact of branched molecular chains in precursor

Constructing flake-like ternary rare earth Pr3Si2C2 ceramic on SiC whiskers to enhance electromagnetic wave absorption properties

Abstract The development of next‐generation 6G communications is anticipated to expand into extreme environments, necessitating superior terahertz (THz) electromagnetic interference (EMI) shielding materials. Herein, structural stability, electronic and optical properties of rare earth silicide carbide Yb3Si2C2 are investigated using first principles density functional calculations and semi‐classical Boltzmann transport theory. The calculation results show Yb3Si2C2 is determined to be experimentally synthesized with high temperature stability with a certain fluctuating C2 pair orientation. In addition, Yb3Si2C2 is identified as a soft, tough, and damage‐resistant ceramic with low shear deformation resistance and easy cleavage, ensuring its durability in irradiation environments. Due to the layered structure and excellent electrical conductivity, Yb3Si2C2 demonstrates high reflectivity and low transmittance for terahertz electromagnetic waves, along with 62% solar absorptivity and 33% IR emissivity. Remarkably, the total shielding effectiveness of Yb3Si2C2 with thicknesses of 5 µm and above follows the widely‐used Simon's formula. The average total shielding effectiveness of 5 µm‐thick and 10 µm‐thick Yb3Si2C2 across the entire THz region reaches 63 and 110 dB, respectively, which turns out to be the top compared to the results reported. Therefore, the multifunctional intrinsic properties of Yb3Si2C2 materials hold great promise for miniaturized, high‐performance terahertz EMI shielding, even in extreme environments.

Enhancing electromagnetic wave absorption performance through construction of three-dimensional multilayered SiCw/Y3Si2C2/Ni0.5Zn0.5Fe2O4 composites

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 (RLmin) 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.

Screw dislocation growth defects enhancing electromagnetic wave absorption performance of GdB6