High-temperature thermal stability modification of (La0.2Y0.2Sm0.2Eu0.2Nd0.2)2Zr2O7 ceramic aerogel for enhanced thermal insulation performance

Abstract

In this study, tetraethylorthosilicate and dimethyldiethoxysilane were employed to modify high-entropy (La0.2Y0.2Sm0.2Eu0.2Nd0.2)2Zr2O7 (5RE2Zr2O7) ceramic aerogels to address the challenges of particle agglomeration and pore structure collapse that occur during the calcination step in the preparation of high-entropy ceramic aerogels. Following the modification, the specific surface area of the ceramic aerogel increased significantly from 32.22 m2/g to 148.65 m2/g to 201.61 m2/g. Simultaneously, the formation of defective fluorite or pyrochlore crystal structures led to reduced thermal conductivity in the three types of high-entropy ceramic aerogels, namely 5RE2Zr2O7 (from 0.212 W m−1•K−1 to 0.139 W m−1•K−1), 5RE2ZSA (from 0.065 W m−1•K−1 to 0.049 W m−1•K−1), and DDS/5RE2ZSA (from 0.046 W m−1•K−1 to 0.039 W m−1•K−1), compared to their respective non-high-entropy counterparts. Balancing the porous structure of high-entropy ceramic aerogels with an adequate number of defective fluorite or pyrochlore crystals is challenging. Addressing this challenge is a key direction for advancing high-entropy aerogels in the future.