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

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 degrees C for x = 0.00, 330 - 370 degrees C for x = 0.05, 210 - 330 degrees C for x = 0.1 and 140 - 210 degrees 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 (M-S) and coercive field (mu H-0(c)) 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 mu B to 1.5 mu B. It was found that the catalytic activity of N2O decomposition of samples increases with increasing nickel content.