Controlled synthesis and magnetic properties of Co1−xNix/MWCNT nanocomposites by microwave irradiation

Highlights: Composition-controlled Co1−xNix alloy nanoparticles attached uniformly on MWCNTs were prepared by microwave irradiation. ► The composition of CoNi can be controlled by adjusting the atomic ratios of metal Co to Ni in the mixed acetate solution. ► Both the Hc and Ms increase with increasing Co concentration from x = 0.8 to 0.5, then decrease from x = 0.5 to 0.2. -- Abstract: Co1−xNix alloy nanoparticles (x = 0.2, 0.5, 0.6, and 0.8) with the diameter 15–28 nm attached on the surface of multi-walled carbon nanotubes (MWCNTs) were prepared to form Co1−xNix/MWCNT nanocomposites by microwave irradiation. Experimental results demonstrated that Co1−xNix alloy nanoparticles with quasi-spherical and face-centered cubic structure had been attached on the MWCNTs, the composition and size of Co1−xNix alloy nanoparticles could be controlled through adjusting the atomic ratios of metal Co to Ni in the mixed acetate solution, the microwave power and microwave irradiation time, respectively. Both the coercivity and the saturation magnetization of Co1−xNix alloy nanoparticles increased with increasing Co concentration from x = 0.8 to 0.5, and decreased when Co concentration was increased from x = 0.5 to 0.2. These confirm that microwave synthesis is promising for fabricating alloy nanoparticles attached on MWCNTs for magnetic storage and ultra high-density magnetic recording applications.