High entropy (LaCeSmEuNd)2Zr2O7 ceramic aerogel with low thermal conductivity and excellent structural heat resistance

Abstract

Dimensions and thermal insulation properties of nanoporous ceramics are unstable at high temperatures due to structural disruptions. This work prepared high entropy (LaCeSmEuNd)2Zr2O7 ceramic aerogel via non-alkoxide sol-gel, supercritical drying, and calcination. XRD and EDS analysis showed that the (LaCeSmEuNd)2Zr2O7 ceramic existed as a single phase. SEM images demonstrated the successful synthesis of aerogel structure. After two hours of annealing at 1200 °C, the cylindrical sample pressed from (LaCeSmEuNd)2Zr2O7 ceramic aerogel had a compressive strength of 58.75 MPa, and its diameter shrinkage was 0.56%, whereas the La2Zr2O7 reached 13.68%. The thermal diffusivity of annealed (LaCeSmEuNd)2Zr2O7 was as low as 0.119 mm2 s−1, and its thermal conductivity at room temperature was 0.073 W·m−1 K−1, which was attributed to lattice disorder, stable porous structure, and abundance of grain boundaries caused by high entropy effects. Extending the high entropy effect to ceramic nano-insulation products is beneficial for enhancing their thermal stability.