The realization of low thermal conductivity at high temperatures (0.11 W m−1 K−1 800 °C) in ambient air in a porous solid thermal insulation material, using stable packed nanoparticles of high‐entropy spinel oxide with 8 cations (HESO‐8 NPs) with a relatively high packing density of ≈50%, is reported. The high‐density HESO‐8 NP pellets possess around 1000‐fold lower thermal diffusivity than that of air, resulting in much slower heat propagation when subjected to a transient heat flux. The low thermal conductivity and diffusivity are realized by suppressing all three modes of heat transfer, namely solid conduction, gas conduction, and thermal radiation, via stable nanoconstriction and infrared‐absorbing nature of the HESO‐8 NPs, which are enabled by remarkable microstructural stability against coarsening at high temperatures due to the high entropy. This work can elucidate the design of the next‐generation high‐temperature thermal insulation materials using high‐entropy ceramic nanostructures.

中文翻译：

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使用稳定的高熵尖晶石氧化物纳米颗粒在高温下实现低热导率和低扩散率


据报道，使用具有 8 个阳离子的高熵尖晶石氧化物纳米颗粒 （HESO-8 NPs） 在多孔固体隔热材料中，在高温 （0.11 W m-1 K-1 800 °C） 下在多孔固体隔热材料中实现低导热率，其堆积密度相对较高，为 ≈50%。高密度 HESO-8 NP 颗粒的热扩散率比空气低约 1000 倍，因此在受到瞬态热通量时，热量传播要慢得多。低导热率和扩散率是通过 HESO-8 NPs 的稳定纳米收缩和红外吸收特性抑制所有三种传热模式（即固体传导、气体传导和热辐射）来实现的，这是由于高熵在高温下对粗化具有显着的微观结构稳定性而实现的。这项工作可以阐明使用高熵陶瓷纳米结构的下一代高温隔热材料的设计。