Modulation of Dielectric Behavior in Ceramic‐Based Materials for Integrated Electromagnetic Waves Absorption and Thermal Conduction

Abstract Multifunctional materials that muster electromagnetic waves absorption (EMA) and thermal conduction features are highly desirable in electronic packaging of advanced electronics. However, traditional carbon‐based and ceramic‐based materials often rely on semiempirical rules when preparing these bifunctional composites because incompatibility between dielectric behavior and thermal conductivity. Herein, two bifunctional materials (SiC@RGO/EP (SCGE) and Si ₃ N ₄ @RGO/EP (SNGE)) with different dielectric features are obtained by assembling 1D ceramics whiskers and 2D graphene sheets to construct 3D porous skeleton followed by epoxy (EP) encapsulation to understand this underlying relationship. Since semiconductor‐type silicon carbide (SiC) ceramics enhance the conductivity and dielectric response of material, thereby significantly intensifying electromagnetic waves loss, the obtained SCGE material harvests remarkable minimal reflection loss values (RL _min ) of −85.92 dB at 2.07 mm, which outperform reported SiC‐based EMA materials so far. Whereas SNGE material prepared by introducing insulator silicon nitride (Si ₃ N ₄ ) ceramics only delivers thermal conductivity (0.86 W m ⁻¹ K ⁻¹ ) close to that of SCGE (0.93 W m ⁻¹ K ⁻¹ ), but EMA performance is dramatically reduced with RL _min of −19.88 dB at 5 mm. The finding of this work offers new insights for modulating dielectric behavior of ceramic materials and carbon‐based materials to achieve the integration of EMA and thermal conduction functions.