High-entropy engineering enables spinel oxides toward high-performance infrared radiation materials

High-entropy engineering, an emerging strategy, has recently received extensive attention for enhancing spinel oxides performance in diverse application fields. Herein, various novel non-equimolar spinel (Co,Mn,Fe,Cr,Ni,Al,Cu) 3 O 4 high-entropy oxides (HEOs) powders were successfully synthesized using a facile and scalable solid-state reaction method, which lied in the appropriate Cu cation content. The in-situ formed flaky alumina from potassium alum thermal decomposition, serving as the source of Al cation, promoted the formation of spinel HEOs powders instead of common reactive alumina powder. In particular, the infrared (IR) radiation performance of (Co 2/13 Mn 2/13 Fe 2/13 Cr 2/13 Ni 2/13 Al 2/13 Cu 1/13 ) 3 O 4 HEOs powder and coating was evaluated. This synthesized HEOs powder possessed a high IR emissivity of 0.885 in the near-IR band (0.78–2.5 µm) and good thermal stability. Notably, its IR emissivity was maintained at 0.874 with only a minimal loss of 1.2 % after high-temperature treatment. More importantly, this synthesized HEOs powder can be functioned as coating on substrates such as the Ti6Al4V alloy plate via the spraying method, exhibiting a superior IR emissivity of 0.925 and impressive radiant heat transfer capability. This work provides a good example of constructing high-performance spinel oxides through high-entropy engineering and holds great potential in developing energy-saving materials for high-temperature furnaces.