Turbulent-centrifugal-spun ceramic aerogels with elemental difference maximization design for thermal protection over 2000 K in air

Thermal protection under ultrahigh temperatures in air remains very challenging due to the severe volume shrinkage and strength degradation induced by rapid grain growth in oxide ceramics, which can potentially lead to catastrophic thermal runaway. Here, we report an elemental difference maximization design of medium-entropy (La 0.5 Y 0.5 ) 2 Zr 2 O 7 fibrous aerogels made by a large-scale and low-cost turbulent-centrifugal spinning method to effectively suppress the grain growth under ultrahigh temperatures over 2000 K in air. The resulting aerogels show an ultrafine grain size of only 405.8 nm, a small volume shrinkage (<3%), and a large strength increase (>26%) after long-term ultrahigh temperature exposure, as well as an ultralow thermal conductivity of 101.1 mW m −1 K −1 at 1273 K and reliable protection performance over 2000 K in air. This work not only establishes a set of fundamental considerations for material design of ceramic aerogels but also promotes large-scale fabrication and practical application of such aerogels for thermal protection under extreme conditions.