STRUCTURAL, MAGNETIC AND OPTICAL PROPERTIES OF Co0.5Ni0.5Fe2O4 NANOPARTICLES SYNTHESIZED BY SOL-GEL AUTO COMBUSTION METHOD

In the present study, Co0.5Ni0.5Fe2O4 ferrite nanoparticles have been synthesized using solgel auto combustion method. The effects of calcination temperature on structural, magnetic and optical properties have been investigated. X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FT-IR) have confirmed the formation of a spinal type of ferrite structure. The average crystallite size of the ferrite samples was between 43.672 and 61.795 nm, which was found to be dependent on the calcination temperature. Morphology studies demonstrated by field emission scanning electron microscopy (FESEM) showed that the grain size increases as the calcination temperature increase. Energy dispersive spectrum (EDS) has also confirmed the presence of Co, Ni, Fe, and O in all samples. The band-gap energy (Eg) has been evaluated using diffuse reflectance spectra (DRS). As the calcination increased, the Eg decreased from 2.388 to 2.055 eV. Furthermore, magnetization measurements for the as-burnt and calcined samples were measured by a vibrating sample magnetometer (VSM), the results showed ferrimagnetic behavior for all samples. Saturation magnetization (MS) increases from 46.1291 to 61.5354 emu/g as the calcination temperature increase. This behavior is related to spin canting and disorder in the surface spin, meanwhile, coercivity values (Hc) of all ferrite samples decrease from 1595 to 558.15 Oe with the increase of the calcination temperature. The squareness ratio (S) lies between 0.50 and 0.56 and the nanoparticles have exchangecoupled interaction.