Magnetic Ordering and Enhancement of Magnetization in Zinc-Substituted Copper Ferrite Nanoparticles

Abstract

ZnxCu1-xFe2O4 (0.05 ≤ x ≤ 0.85) nanoparticles were synthesized by sol-gel method and were annealed at 500 and 900 °C in air for 3 h. Characterization techniques like XRD, Raman spectroscopy, and vibrating sample magnetometer were used to investigate phase, cation distribution, and magnetic properties. XRD studies showed that all the as-prepared samples are of cubic spinel phase. Tetragonal phase was observed in the samples with x < 0.15 after annealing, whereas all other samples retained cubic phase. Raman spectroscopy showed increase of Zn2+ ions in the tetrahedral site with the increase in Zn2+ concentration in the nanoparticle samples. Cation distribution and magnetic ordering enhanced the magnetization value with increasing x value, and a maximum was observed in the as-prepared and annealed samples. The coercivity decreased with the increase in Zn2+ concentration. The highest magnetization value of 110 emu/g with coercivity of 25 Oe was observed in the present study at 60 K for the sample annealed at 900 °C with x = 0.5. Law of approach to saturation method was adopted to study the magnetic ordering in the nanoparticle samples. The blocking temperature decreased with increase in Zn2+ concentration and annealing temperature. Cation distribution associated magnetic ordering and anisotropy variation with the increasing Zn2+ concentration explains the observed magnetic behavior in these nanoparticle samples.