## 3 Results and Discussion
### The Influence of Different Cu and Ni Contents on Magnetic Properties
Therefore, we can be sure that we are dealing with soft ferrite in this series. For the magnetic flux of [Ni\({}_{x}\)Zn\({}_{1-x}\)]Fe\({}_{2}\)O\({}_{4}\) ferrite, further calculations from the formula showed that the units of magnetic flux (B) were gauss. From the results, it can be seen that the magnetic flux for Ni\({}_{0.2}\)Zn\({}_{0.8}\) was 61.18 gauss/g. For Ni\({}_{0.3}\)Zn\({}_{0.7}\), the magnetic flux dropped to 14.00 gauss/g; later on, as Ni content increased, the magnetic flux also increased. When the composition was Ni\({}_{0.5}\)Zn\({}_{0.5}\), it reached a peak of 624.48 gauss/g, but when the composition was Ni\({}_{0.64}\)Zn\({}_{0.36}\), the magnetic flux decayed to 416.06 gauss/g. This trend was the same as the magnetic flux trend described in the literature [22; 23]. The magnetic flux increases with the rise in Ni\({}^{2+}\) ions concentration. The Effect of the Sintering Temperature on the Crystal Phase of [Cu\({}_{x}\)Zn\({}_{1-x}\)]Fe\({}_{2}\)O\({}_{4}\) and [Ni\({}_{x}\)Zn\({}_{1-x}\)]Fe\({}_{2}\)O\({}_{4}\)  
Figure 4a shows the XRD diagram of Cu\({}_{0.7}\)Zn\({}_{0.3}\)Fe\({}_{2}\)O\({}_{4}\) at different sintering temperatures. The material was sintered in an air atmosphere, at 5 \({}^{\circ}\)C/min, and after a constant temperature maintained for 2 h the furnace was cooled. From the experimental results, it is clear that as the sintering temperature increased, the crystal phase became more integrated and its strength became stronger. Under the air sintering temperature and atmosphere, part of it suffered thermal decomposition due to over-heating; therefore, nitrogen was not needed in the sintering process. For the ferrite composition of Cu\({}_{0.7}\)Zn\({}_{0.3}\)Fe\({}_{2}\)O\({}_{4}\), using the diffraction peaks at different sintering temperatures and the Scherrer equation, the average particulate diameter was calculated. And as temperature increased, the original particulate diameter of 24.65 nm at 500 \({}^{\circ}\)C increased to 94.46 nm at 900 \({}^{\circ}\)C. Thus, as the temperature increased, the particulate diameter also increased. Figure 4b shows the XRD diagram of Ni\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) at different sintering temperatures, sintered in an air atmosphere at 5 \({}^{\circ}\)C/min, held at a constant temperature for 2 h, and finally furnace-cooled. The experimental results show that as the sintering temperature increased, the crystal phase became more integrated and its strength became stronger. This was unlike the [Mn\({}_{x}\)Zn\({}_{1-x}\)]Fe\({}_{2}\)O\({}_{4}\) system under air atmosphere, as when the sintering temperature was too high, thermal decomposition occurred. Therefore, N\({}_{2}\) was not needed for sintering. For Ni\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) ferrite at different sintering temperatures, the diffraction peaks were used to calculate the average particulate diameters, and it was seen that the particulate diameter increased with the temperature increase. The particulate diameter increased from the original 20.31 nm at 500 \({}^{\circ}\)C to 201.06 nm at 1200 \({}^{\circ}\)C. The XRD diagram confirmed the single crystalline phase of the nanoparticles. The lattice parameter decreased with the increase in Ni content and reduced lattice strain.