The Reflection of Cr/Fe Substitution on the Structural, Magnetic and Photoluminescence Features of Zn–Ni Based Ferrite

Abstract

In this work, we substituted iron by chromium in the nano-spinel ferrite Ni0.5Zn0.5Fe2O4 (NZF), then we studied how relevant the structure, magnetic, and optical characteristics of the produced samples are changed accordingly. This doping caused a redistribution of Fe, Zn, and Ni ions over tetrahedral and octahedral sites as confirmed from XRD Reitveld analysis. Upon Cr/Fe substitution, a decrease in the lattice parameter occurred accompanied by a decrease in crystallite size of the doped samples. Magnetic measurements indicated the decrease of saturation magnetization by increasing the amount of Cr doping. On the other hand, the coercivity (Hc) increases about six times from Cr content x = 0.0 (28.28 Oe) to x = 1.0 (192.25 Oe). Photoluminescence (PL) measurements at 650 nm excitation showed emission peaks arising from Fe3+ transitions, band-to-band transitions, oxygen defect-related emission, and Cr3+ transitions that appeared strongly at heavily doped NZF with Cr. The PL intensity quenches strongly with increasing Cr/Fe ratio due to concentration, mobility, and generation of non-radiative center effects. The band gap energy of the Cr-doped NZF system is red shifted until x = 0.5 and the increases (blue shifted) at x = 0.75.