Managing the Magnetic Properties of NiCo/C Nanocomposites

The creation of new types of radio-absorbing materials (RAMs) is relevant due to the intensive development of microwave radio electronic devices, their increasing power, and their active implementation in all spheres of life. A RAM based on NiCo/C nanocomposite can be used to reduce the interference and ensure the electromagnetic compatibility. The NiCo/C metal-carbon nanocomposites based on the NiCl2/CoCl2/polyacrylonitrile (PAN) precursors are synthesized using IR heating. The results of studies of NiCo/C nanocomposites by X-ray phase analysis (XPA), transmission electron microscopy, and vibration magnetometry show the dependence of the structure and properties of NiCo/C nanocomposites on the synthesis temperature, concentration, and metal ratio in the precursor. The results of XPA shows the formation of NiCo metal nanoparticles that have been stabilized in the carbon matrix during the IR pyrolysis of the precursor. Increasing the synthesis temperature from 350 to 800°C leads to the average size of NiCo nanoparticles growing from 10 to 80 nm. It is found that the formation of the alloy occurs due to the gradual dissolution of cobalt in nickel with the simultaneous transition of cobalt from the hcp modification to FCC. The structure of nanocomposites is studied by the transmission electron microscopy of the samples synthesized at 600°C. It is found that an increase in the metal concentration in the precursor from 10 to 40 wt % increases both the average size of NiCo nanoparticles in the NiCo/C nanocomposite content and the concentration of the nanoparticles in the carbon matrix. The study of the magnetic properties of nanocomposites shows an almost linear increase in the saturation magnetization from 5.94 to 25.7 A m2/kg with an increase in the content of metals in the precursor from 10 to 40 wt %. The change in the ratio of metals from Ni : Co = 4 : 1 to Ni : Co = 1 : 4 results in the magnetization increasing from 11.46 to 23.3 A m2/kg.