A study on microstructure and magnetic properties of nanostructured CoxNi1-xMn0.5Fe1.5O4(x = 0, 0.25, 0.5, 0.75, 1) spinel ferrites

Abstract

A low-temperature synthesis of novel nanostructured Cox Ni1-x Mn0.5 Fe1.5 O4 (x = 0, 0.25, 0.5, 0.75, 1) ferrites was carried out by sol-gel auto-combustion technique. The obtained nanostructured ferrites were investigated by employing the techniques of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). The XRD diffractograms of the prepared ferrites revealed the formation of a spinel phase with facecentered cubic (fcc) structure belonging to the Fd-3m space group. The average lattice parameter ‘a' of ferrites exhibited a rise versus a rise in Co2+ concentration following Vegard's law. The SEM investigation of NiMn0.5Fe1.5O4 powder revealed the existence of octahedral-shaped morphology of ferrite grains. The TEM investigation of NiMn0.5Fe1.5O4 powder showed nanostructures of ferrite particles with sizes consistent with the crystallite sizes as estimated by Debye-Scherer's formula. An EDX spectrum of NiMn0.5Fe1.5O4 powder confirmed its elemental composition. The M-H hysteresis loops recorded by VSM at room temperature revealed a dependence of coercivity (Hc), maximum magnetization (Mmax), and retentivity (Mr) on Co2+ concentration. The shape dependence of M-H loops on Co2+ concentration in compounds enabled their candidature for applications in memory devices and magnetic sensors.