“…On the other hand, the formation of face-centered cubic spinel structure of ZnAl 2 O 4 is confirmed by the presence of the diffraction peaks located at 31.26°, 36.97°, 44.97°, 49.2°, 55.92°, 59.43°, 65.37°, 74.2°, and 77.5°, which correspond to the planes of ( 220), ( 311), ( 400), ( 331), ( 422), ( 511), ( 440), (620), and (533), respectively, as shown in Figure 2 (b) (Xing et al, 2020). However, the appearance of additional peaks in the ZnAl 2 O 4 XRD pattern indicates the presence of an impurity phase, mainly attributed to the formation of zinc oxide (Xing et al, 2020). This is verified by the refinement to the XRD pattern, as seen in Figure 2 (d), where 88.2 and 11.8% of ZnAl 2 O 4 and ZnO phases, respectively, were obtained.…”