High-Temperature Wave-Transparent Alumina Lattices Combining Heat Dissipation and Mechanical Protection

Electromagnetic (EM) wave‐transparent structures with mechanical robustness and high‐temperature resistance are highly desirable for protecting communication systems, particularly in harsh environments. While heat dissipation has received comparatively little attention, it is an effective means to mitigate safety risks by reducing operating temperatures. Herein, we present a straightforward strategy for fabricating heat‐dissipative and wave‐transparent Al2O3 structures with diamond lattice architectures, thereby enlarging the surface area to enhance heat exchange efficiency while maintaining high‐temperature resistance. The resulting diamond‐structured Al2O3 exhibits an average dielectric constant (ε′) of 2.32 and a low loss tangent (tan δ) of 0.0031, achieving over 90 % EM‐wave transmittance across the entire X band. The structure also demonstrates excellent high‐temperature resistance, maintaining an average transmittance of 93.73 % at 600 °C and negligible performance variation after annealing at 1000 °C in air. Notably, the diamond‐structured Al2O3 delivers superior heat dissipation, cooling to 55 °C within 39 s under airflow. In addition, it exhibits high mechanical robustness owing to the optimal particle grading that enhances bonding. The specific compressive strength, Young’s modulus, and energy absorption values reach 220.71 MPa, 12.12 GPa, and 277.06 kJ/cm3, respectively, making it a promising candidate for mechanical protection in extreme conditions without compromising EM‐wave transmission.