Solid Phase Synthesis of Cobalt Ferrite Under the Action of a DC Glow Discharge at Atmospheric Pressure

The paper presents a novel method for obtaining cobalt ferrites with a spinel type structure under the action of a nonequilibrium atmospheric pressure gas-discharge plasma in air on a mixture of solid iron and cobalt hydroxonitrates. The data of energy dispersive X-ray spectroscopy and X-ray phase analysis showed that the synthesized powders have a complex phase and chemical composition, which depends on the Fe:Co molar ratio in the initial salts. The best result in terms of yield of cobalt ferrite is obtained with Fe:Co = 2:1. The resulting material contains 86 wt% Fe₂CoO₄, also 13.5 wt% Fe₂O₃ and 0.5 wt% Fe₃O₄. At other ratios, Co₃O₄ is also formed. According to dynamic light scattering data, the obtained powders consist of two characteristic fractions. The main fraction (94%) is represented by particles 105 ± 4 nm in size. And the other fraction (6%) consists of particles 18 ± 4 nm in size. The resulting materials have magnetic properties. So, for powders obtained from salts with Fe:Co = 2:1 the coercive force was \(\sim\) 490 Oe. The saturation magnetization was \(\sim\) 52 emu/g, and the remnant magnetization was \(\sim\) 22 emu/g.