Citrate-gel auto combustion technique was used to synthesize nickel-copper mixed ferrite nanoparticles NixCu1-xFe2O4 (x= 0.0, 0.4, 1.0) with different calcinating temperatures (200, 450, 650 and 850 °C). Structural, morphological, magnetic, and electrical properties were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and LCR meter in order to determine significant influences of Cu2+ cations content in nickel ferrite. The XRD patterns showed that all compositions had cubic spinels, except CuFe2O4 samples. The system structure in Cu-ferrite was deformed at 650 °C  from a cubic to a tetragonal system with a secondary phase CuO. Lattice constant was decreased with increasing Cu2+ cations substitution in Ni-ferrites, while crystalline volume was increased. With the help of Debye-Scherrer`s equation using XRD data, we found that the crystallite size at 850 °C is lying in the range from 38.70  to 48.00 nm. The FTIR spectrum of samples under investigation showed two significant absorption bands, which refer to the formation of a single-phase cubic spinel. The magnetization test revealed a soft ferromagnetic behavior for all the compositions sintered at 850 °C. The saturation magnetization (Ms) was decreased with the substitution by Cu2+ cations, while remnant magnetization (Mr) and coercivity (Hc) were increased in Cu-ferrite. The highest Ms value was 42.25 emu.g-1 for Ni-ferrite, while the highest Hc value was 517.16 Oe for Cu-ferrite. The electrical measurement of samples showed an increase in the real dielectric constant and AC conductivity at a frequency range of 20Hz-3MHz with the addition of copper cations.

Pulsed laser ablation in liquid (PLAL) is considered a relatively fast, simple to manipulate, cost-effective abraoch, and enables the fabrecation of multiscale micro-nanostructures in one step, facilitating the fabrication process. Copper nanoparticles solution was prepared by PLAL technique using Nd:YAG laser in deionized water at (532 nm), (1000 pulse), and the energies (700 mJ, 800 mJ, 900 mJ, and 1000 mJ) with a fixed distance between the laser source and the sample, fixed amount of liquid, and the liquid rise above the copper was (5 mm). The effect of the excess of the laser energy in the preparation process was tested by analyzing the optical properties of the fabrecated samples by UV-Visible spectrophotometer, SEM, XRD, and EDX measurements.