Synthesis, characterizations, and magnetic behavior of novel (CuNiTiZnFe)3O4 high entropy spinel oxide

Abstract

In this report, a modified solid-state synthesis technique is optimized to synthesize a single spinel phase for a novel (CuNiTiZnFe)3O4 High Entropy Oxide (HEO) and studied for magnetic behavior. Three different approaches were adopted for the synthesis of pure spinel HEO. In the first approach, The initial mixture of constituent oxides was admixed, and sintered at 1050 °C for 20 h. For the second and third approaches, the mixture of constituent oxides was ball-milled for 2 h, and 10 h separately, followed by sintering at 1050 °C for 20 h. A small amount of undiffused constituent oxide peaks are present in both the first and second approaches. However, the sample synthesis through 10 h milling followed by sintering has single spinel (CuNiTiZnFe)3O4 HEO phase. The single spinel HEO phase formation was confirmed through the le-Bail refinement. The lattice parameter for the well-fitted XRD pattern is 8.415161 A°. Further, the investigation was focused on the magnetic behavior of the single spinel HEO phase. The value of magnetization and coercivity is 16.11 emu/g and 10.66 Oe, respectively. The synthesized HESO has typical ferrimagnetic nature and has the second-highest value of Ms reported so far for HEOs. The ionic states of different cations present in the (CuNiTiZnFe)3O4 HESO were also investigated through X-ray photoelectron Spectroscopy. XPS analysis reveals that Fe and Ni are in the +3 and + 2 states, Cu and Zn are in the +2 states, and Ti is in the +4 states.