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

ZnxCu1-xFe2O4(0.05 <= x <= 0.85) nanoparticles were synthesized by sol-gel method and were annealed at 500 and 900 degrees 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 withx< 0.15 after annealing, whereas all other samples retained cubic phase. Raman spectroscopy showed increase of Zn(2+)ions in the tetrahedral site with the increase in Zn(2+)concentration in the nanoparticle samples. Cation distribution and magnetic ordering enhanced the magnetization value with increasingxvalue, and a maximum was observed in the as-prepared and annealed samples. The coercivity decreased with the increase in Zn(2+)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 degrees C withx = 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 Zn(2+)concentration and annealing temperature. Cation distribution associated magnetic ordering and anisotropy variation with the increasing Zn(2+)concentration explains the observed magnetic behavior in these nanoparticle samples.