Effects of Ni doping on structural, magnetic and catalytic properties of copper ferrite

•The influence of nickel in ferrites on the phase transition from tetragonal to cubic.•Replacing Cu with Ni improves the catalytic activity of N2O decomposition in ferrites.•Magnetic moment values per formula unit are estimated to range from 1.16 μB to 1.5 μB. The aim of this work was to obtain information about the influence of small quantities of Ni2+ ion on the structural and magnetic properties of the tetragonally distorted of Cu1−xNixFe2O4 series (with x = 0.00, 0.05, 0.1, and 0.15 respectively). The tested ferrite system was synthesized by combustion of citrate–nitrate precursors. The synchrotron X-ray diffraction measurements determined the phase transition temperatures (tetragonal → cubic) of all samples. The change of structures under the influence of temperature shows a phase transition in the range of 390 – 400 °C for x = 0.00, 330 – 370 °C for x = 0.05, 210 – 330 °C for x = 0.1 and 140 – 210 °C for x = 0.15, respectively. The initial phase transition temperature decreases linearly with the decreasing c/a ratio of the crystallographic lattice parameters for the Cu1−xNixFe2O4 oxides. Hysteresis measurements were made to determine the saturation magnetization (MS) and coercive field (µ0Hc) of the samples. The values of magnetic moments at room temperature determined from magnetization measurements are very similar to those obtained from theoretical x-ray diffraction calculations. Magnetic moment values per formula unit are estimated to range from 1.16 μB to 1.5 μB. It was found that the catalytic activity of N2O decomposition of samples increases with increasing nickel content.