Facile preparation of single phase high-entropy oxide nanocrystalline powders by solution combustion synthesis

Abstract High-entropy oxides (HEOs), due to their excellent physicochemical properties, have attracted extensive attention. In this work, the solution combustion synthesis approach was applied to prepare a series of porous single-phase HEO nanocrystalline powders. Equiatomic (Co 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 )O, (Cr 0.2 Fe 0.2 Mn 0.2 Mg 0.2 Zn 0.2 ) 3 O 4 and (Ce 0.2 La 0.2 Pr 0.2 Sm 0.2 Y 0.2 )O 2 were successfully obtained. While the former two could be stabilized into single rock-salt (Fm-3m) and spinel (Fd-3m) structures, the latter could be synthesized to have either CaF 2 -type (Fm-3m) or CaF 2 -related-type (Ia-3) structure depending on synthesis temperature. Furthermore, their chemical and microstructural homogeneity was further confirmed.