6 Nanocomposites and nanomaterials

Magnetic properties of Ni-doped CoFe2O4 nanoparticles obtained by the plasma method

L. A. Frolova, A. A. Pivovarov, R. V. Shpatakova

Department of Technology Inorganic Materials and Ecology, Ukrainian State University of Chemical Technology, Dnipro, Ukraine, ave Gagarina, 8, Dnipro-49005, Ukraine.
E-mail: 19kozak83@gmail.com

Nanodispersed spinel ferrites with a complex stoichiometry are materials having a wide field of use. For example, in power engineering, electronics, adsorption, catalysis, in water purification systems, etc. Many researchers are considering new technologies for the synthesis of Co-Ni ferrites: coprecipitation, ceramic, organic precursor combustion, hydrothermal method, emulsion method. Nevertheless, the development of cheap and high-performance processes for the production of spinel ferrites remains relevant. Variation of such factors as the initial pH, temperature, cation composition and precursors affects the magnetic properties of ferrites.
In this paper, we consider a series of mixed ferrites of cobalt and nickel synthesized using contact low-temperature nonequilibrium plasma. The synthesis was carried out in a plasma-chemical reactor at various pH values (8–12), processing time (5–20 minutes), temperature (20–40 °C). The relative magnetic characteristics were determined by a vibration magnetometer. The saturation magnetization and the coercitivity were determined from the hysteresis loop.
The influence of main factors on the magnetic characteristics of the final product was studied on the basis of a full three factorial experiment. The results of an experimental study show that the values of saturation magnetization and coercivity vary depending on various factors.
Was established that the coercivity of the samples obtained significantly depends on the processing time and temperature. Analysis of the models obtained showed that the main factor influencing the Мs is the initial pH of the treated suspension. An increase in temperature leads to an increase in the coercive force and a slight decrease in magnetization. This is due to an increase in the oxidation rate, which, with some combination of factors, leads to the formation of a defective structure.