“…In Figure 1i(i), we have observed the planes (111), (002), (022), and (222) at 2θ values of 33, 42.7, 62, and 78.2°,respectively, corresponding to the cubic phase of cobalt oxide (CoO) in the shell with a space group of Fm3m (HighScore Plus reference code: 98-005-3057). Additionally, the planes (111), ( 022), ( 113), ( 222), ( 004), ( 133), ( 224), ( 115), ( 004), (135), and (026) at 2θ value of 18,30,35,37,43,47,53,57,62,66, and 71°ensure the development of Ni 0.75 Zn 0.25 Fe 2 O 4 in the core with cubic crystal phase having space group of Fd3̅ m with the reference code 98-016-3785. Hence, the formation of Ni 0.75 Zn 0.25 Fe 2 O 4 @CoO is confirmed in the case of system 1.…”