## 3 Results and Discussions
### The Effect of Sintering Temperature on the Crystal Phase and the Magnetic Properties
Surface Morphology and Compositional Analysis of [Mn\({}_{\rm 0.54}\)Zn\({}_{\rm 0.46}\)]Fe\({}_{\rm 2}\)O\({}_{\rm 4}\)  
Figure 6 shows the surface morphology for [Mn\({}_{\rm 0.54}\)Zn\({}_{\rm 0.46}\)]Fe\({}_{\rm 2}\)O\({}_{\rm 4}\) that is produced from waste batteries with different pH values. For all compositions, the Mn-Zn ferrites show similar morphology and very strong agglomeration due to magnetic particles, and particles that are of uniform grain size. It is seen that when the pH value is 6, the average particulate diameter is very small, at about 10 nm. There is a laminate structure, when the pH value is 7, but the average particulate diameter remains at about 10 nm. The laminate structure decays when the pH has a value of 8 because the particles begin to cluster into ball shapes. The laminate structure almost disappears when the pH is 9 and totally disappears at a pH of 10, when only nanoparticles that are clustered into spherical shapes remain. The average particulate diameter increases significantly to about 40 nm and there is no laminate structure when the pH value is 11. It is seen that for a pH value of 12, the average particulate diameter is smaller than that for a pH of 10, at about 20-30 nm, and there is no laminate structure. The average particulate diameter is only about 10 nm. The laminate structure is only present at pH values of between 6 and 9, so it is reasonable to assume that the laminate structure is composed of metallic oxide that undergoes an incomplete acid or alkaline neutralization reaction. Table 2 shows that the mean particulate diameter for [Mn\({}_{\rm 0.54}\)Zn\({}_{\rm 0.46}\)]Fe\({}_{\rm 2}\)O\({}_{\rm 4}\) is correlated with the size that is estimated from SEM and XRD using the pH value. The mean diameter for [Mn\({}_{\rm 0.54}\)Zn\({}_{\rm 0.46}\)]Fe\({}_{\rm 2}\)O\({}_{\rm 4}\) exhibits the same variation for the range of sintering temperatures studied. The energy dispersive detector (EDS) composition analysis diagram for [Mn\({}_{\rm 0.54}\)Zn\({}_{\rm 0.46}\)]Fe\({}_{\rm 2}\)O\({}_{\rm 4}\) shows that ferrite is an alloy that is formed from four elements: Mn, Zn, Fe and O. It contains no other metallic atoms. The studied proportions are correct and it is proven that the metallic ions are completely precipitated during the neutralization process. Figure 6: _Cont._  
Figure 6: The surface morphology of [Mn\({}_{0.54}\)Zn\({}_{0.46}\)]Fe\({}_{2}\)O\({}_{4}\) that is produced from waste dry batteries with different pH values: (**a**) pH = 6, (**b**) pH = 7, (**c**) pH = 8, (**d**) pH = 9, (**e**) pH = 10, (**f**) pH = 11 and (**g**) pH = 12. The Effect of the Sintering Temperature in a \(N_{2}\) Environment on the Crystal Phase and the Magnetic Properties  
Figure 7a shows the XRD diagram for [Mn\({}_{0.54}\)Zn\({}_{0.46}\)Fe\({}_{2}\)O\({}_{4}\) that is sintered in a N\({}_{2}\) environment at 700 \({}^{\circ}\)C to 950 \({}^{\circ}\)C. When the ferrite is sintered at a temperature of more than 600 \({}^{\circ}\)C, there is oxidation, so a N\({}_{2}\) environment is used. Ferrite that is sintered in a N\({}_{2}\) environment does not contain \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\). Table 1 shows the data for [Mn\({}_{x}\)Zn\({}_{1-x}\)]Fe\({}_{2}\)O\({}_{4}\) that is sintered at different temperatures in a N\({}_{2}\) environment. The average particulate diameter is calculated using the diffraction peaks. It is seen that when the sintering temperature is 700 \({}^{\circ}\)C, the particulate diameter is 95.03 nm. An increase in sintering temperature results in an increase in the average particulate diameter. At 800 \({}^{\circ}\)C, the value is a maximum at 119.08 nm. The value then begins to decrease and at 950 \({}^{\circ}\)C, it is 96.02 nm. When the material is sintered for too long in a N\({}_{2}\) environment, oxygen atoms escape from [Mn\({}_{0.52}\)Zn\({}_{0.46}\)]Fe\({}_{2}\)O\({}_{4}\).