High-Entropy Ceramic Aerogel with Ultrahigh Thermomechanical Properties

Materials for extreme-condition thermal insulation need to simultaneously withstand complex thermomechanical stresses while retaining their insulating properties at high temperatures. Ceramic aerogels are attractive candidates, but conventional low-entropy ceramics usually suffer from formidable grain growth with severe volume shrinkage and strength degradation, resulting in catastrophic failures. Herein, a high-entropy (La_1/4Sm_1/4Gd_1/4Y_1/4)₂Zr₂O₇ (ZLSGY) aerogel is made through an element-phase design, realizing enhanced lattice distortion and sluggish diffusion effects to achieve fine-grain strengthening under extreme conditions. The resulting aerogel exhibits excellent mechanical flexibility, achieving compressive, tensile fracture, and bending strains of 98%, 52%, and 99%, respectively, as well as an ultralow thermal conductivity of 24.79 mW m^-1 K^-1 at 25 °C and 82.19 mW m^-1 K^-1 at 1000 °C. Moreover, the aerogel achieves exceptional thermomechanical stability with a working temperature of up to 1400 °C (less than 3% strength degradation after 10⁵ high-temperature deformation cycles). This high-entropy ceramic aerogel presents a promising material system for thermal insulation in extreme environments.