Magnetic properties of dysprosium-doped cobalt ferrite nanoparticles synthesized by starch-assisted sol-gel auto-combustion method

Abstract

Dysprosium-substituted cobalt ferrite nanoparticles with composition of CoFe<inf>2−x</inf>Dy<inf>x</inf>O<inf>4</inf> (x = 0 − 0.1 in a step of 0.025) were synthesized by starch-assisted sol–gel auto-combustion method. The effect of Dy3+ cation substitution on structural and magnetic properties of cobalt ferrite nanoparticles was investigated. Powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, infrared spectroscopy (IR), X-ray photoelectron spectroscopy and vibrating sample magnetometer (VSM) were employed to characterize the physical properties of these ferrite nanoparticles. XRD pattern reveals the formation of cubic spinel ferrite with the signature of DyFeO<inf>3</inf> phases for x ≥ 0.05. An infrared spectroscopy study shows the presence of two absorption bands in the frequency range around 560 cm−1 (ν<inf>1</inf>) and around 380 cm−1 (ν<inf>2</inf>), which indicate the presence of tetrahedral and octahedral group complexes, respectively, within the spinel ferrite nanoparticles. FE-SEM analysis indicated the formation of nanosized particles (5 −15 nm) with spherical morphology. Vibrating sample magnetometer was employed to probe the magnetic properties of the samples at room temperature. It was observed that rare earth ion dopant, crystallite size and foreign phase DyFeO<inf>3</inf> affect the magnetic properties of cobalt ferrite nanoparticles. © 2015, Springer Science+Business Media New York.