MAGNETOTHERMAL PROPERTIES OF COPPER FERRITE

Abstract

In this work, we carried out the directed synthesis of copper ferrite (CuFe2O4) by co-precipitation from solutions with an excess of alkali at a temperature of 373 К. The methods of scanning electron microscopy and X-ray phase analysis were used to study the crystal structure and surface morphology of copper ferrite. The ratio of the characteristic peaks of the diffractogram was carried out in accordance with the JCPDS database. It is shown that copper (II) ferrite crystallizes in the structure of the cubic spinel. Microphotographs of the synthesized copper ferrite samples at different magnifications are given. It is established that ferrite particles consist of conglomerates of crystals with different sizes of individual grains. Their small scatter in size is observed. The average particle size is in the range of 100-200 nm. Using a dynamic heat flux differential scanning calorimeter, the temperature dependence of the heat capacity of copper ferrite samples was obtained in the temperature range of 273–373 K. Using an original microcalorimetric setup in the temperature range of 288–346 K and with a change in the magnetic field induction from 0 to 1.0 T, thermodynamic characteristics were obtained - the magnetocaloric effect (MCE) and the change in entropy (ΔS) during the magnetization of copper (II) ferrite. It was found that with an increase in the magnitude of the magnetic field, the magnitude of the MCE increases and decreases with increasing temperature. It was found that the temperature dependences of the magnetocaloric effect and specific heat have an extreme character. In the region of room temperatures (308–315 K), a maximum of the magnetocaloric effect and a minimum of the specific heat are observed. This previously unknown anomalous behavior of the magneto-thermal properties of copper II ferrite was discovered for the first time.