Synthesis, structure and properties of Zn0.3Ni0.7-xCoxFe2O4 (x = 0-0.6) ferrite

For many years, Ni-Zn ferrites with the spinel structure have actively been used as various components for RF devices. An analysis of modern scientific literature has been carried out, as a result of which an alloying element has been determined that will change the complex of physicochemical properties of the initial matrix of Ni-Zn ferrite. The article presents the results of a study of the Zn0.3Ni0.7-xCoxFe2O4 ferrite, where x takes the value 0-0.6 in increments of 0.2. In addition to the alloying element, the properties of the samples under study are affected by selection of the method of obtaining the material, as well as the temperature-time mode of synthesis. The samples have been obtained by the solid-phase synthesis in a tube furnace with silicon carbide heaters at a temperature of 1150 °C for 5 hours of isothermal exposure. The objective of the present study is to obtain new compositions of nickel-zinc ferrite doped by cobalt according to the already known technology for a wider concentration range, as well as investigate their properties. The chemical composition has been analyzed on a Jeol JSM 7001F scanning electron microscope equipped with an Oxford INCA X-max 80 X-ray dispersion spectrometer to determine the actual gross formula of sintered samples, the results of which are in good agreement with the theoretical given formulas. As a result of X-ray phase analysis (RigakuUltima IV), it has been found that all the samples under study are monophasic and have the spinel structure with an Fd-3m space group. Unit cell parameters monotonically increase with increasing cobalt concentration x (Co) (from 8.3643 (4) Å to 8.3983 (4) Å). As a result of the study of DSC curves (Netzsch, STA 449 F1 Jupiter), it has been found that partial replacement of Ni and Zn ions by cobalt ions leads to a decrease in the Curie temperature (from 341 °C to 419 °C). Since ferrite parts are used at various temperature conditions, such alloying makes it possible to effectively control the range of working temperatures of the material.