A novel high-entropy (Sm_0.2Eu_0.2Tb_0.2Dy_0.2Lu_0.2)₂Zr₂O₇ ceramic aerogel with ultralow thermal conductivity

Here, we report a novel high-entropy rare earth zirconate (HE-REZ) (Sm_0.2Eu_0.2Tb_0.2Dy_0.2Lu_0.2)₂Zr₂O₇ ceramic aerogel prepared through a sol-gel template method and high-temperature calcination followed by 3-D-structure reconstruction. The structural evolution and crystallisation behaviour of the prepared aerogel were characterised through scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The results indicated that the as-prepared HE-REZ ceramic aerogels had a typical nanoporous structure. The HE-REZ ceramic aerogels thermally treated at 900 °C presented an ultralow room temperature thermal conductivity of 0.031 W/(m·K), high specific surface areas of 443.26 m²/g and a relatively high strength of 12.95 MPa. The effects of different calcination temperatures on the microstructure of the samples were also investigated. Therefore, the excellent insulation performance of these unique HE-REZ ceramic aerogels indicate that they can be used as high-temperature insulators for hypersonic vehicles in the future.