A new class of spinel high-entropy oxides with controllable magnetic properties

A new class of high-entropy spinel oxides, (Cr0.2Fe0.2Mn0.2Ni0.2Zn0.2)(3)O-4 and (Cr0.2Fe0.2Mn0.2Co0.2Zn0.2)(3)O-4 nanocrystalline powders, has been synthesized by solution combustion synthesis. Their microstructures and magnetic properties were compared with those of (Cr0.2Fe0.2 Mn0.2Co0.2Ni0.2)(3)O-4. All the oxides were identified to have the spinel crystal structure (Fd-3m) with average crystallite size of about 24 nm, and their lattice parameters found to decrease with reduction in the electronegativity of Ni2+, Co2+ and Zn2+. Furthermore, nonmagnetic Zn2+ substitution for either magnetic Co2+ or Ni2+ weakened the ferromagnetic ordering and magnetic moments, showing the controllable magnetic property of this new class of high-entropy oxides.