Tunable Synthesis, Thermal Stability and Magnetic Properties of CoCrxCuFeNi@C High-Entropy Alloy Nanoparticles

The addition of Cr offers new opportunities for both fundamental and applied research on magnetic nanoparticles by diversifying the tunability of magnetic properties in high-entropy alloy (HEA) nanoparticles. This paper reports a novel method based on metal-organic chemical vapor deposition (MOCVD) for synthesizing CoCr[Formula: see text]CuFeNi@C nanoparticles with adjustable Cr content. Uniform CoCr[Formula: see text]CuFeNi@C nanoparticles, with sizes below 10[Formula: see text]nm, were synthesized by pyrolyzing the gaseous acetylacetonates of Co, Cr, Cu, Fe and Ni at [Formula: see text]C. It was observed that increasing the Cr content (0–20%) progressively reduces the onset temperature for oxidation from 262[Formula: see text]C to 199[Formula: see text]C. The as-synthesized nanoparticles exhibited typical soft magnetic behavior due to their small size. The saturation magnetization decreased from 38.6[Formula: see text]emu/g to 17.0[Formula: see text]emu/g, while the coercivity initially decreased from 112[Formula: see text]Oe to 10[Formula: see text]Oe and then increased to 67[Formula: see text]Oe, a result of the combined effects of lattice distortion-induced magnetic anisotropy and the Cr atom dilution effect. This study demonstrates a cost-effective and versatile approach for synthesizing CoCr[Formula: see text]CuFeNi@C nanoparticles with tunable elemental composition, thermal stability, and magnetic properties. The as-synthesized CoCr[Formula: see text]CuFeNi@C nanoparticles show promising potential for applications in magnetic sensors, drug delivery carriers, electromagnetic wave absorption and shielding materials.