Effect of calcination temperature and cobalt addition on structural, optical and magnetic properties of barium hexaferrite BaFe12O19 nanoparticles

Abstract

(xCo)-BaFe12O19 nanoparticles, with 0 $$\le x \le$$ 0.1 wt%, have been prepared using a chemical co-precipitation method and different calcination temperatures (850 °C, 900 °C and 950 °C). The samples were subjected to structural, optical and magnetic studies. X-ray powder diffraction showed the hexagonal crystal structure of (xCo)-BaFe12O19, and the more convenient temperature for the formation of this phase was 950 °C. Transmission electron microscope was used for investigating the morphology as well as the average particle size of the samples. It was found that the average size of all samples ranges between 65 and 90 nm. The energy band gap Eg was determined using UV–Vis spectroscopy. It was noticed that the values of Eg decreased with the addition of cobalt and the increase in the calcination temperature. The M–H curve obtained from vibrating sample magnetometer has been used to study the magnetic behavior. The anisotropy field (Ha), the saturation magnetization (σs), the effective crystalline anisotropy constant (Keff), the remanent magnetization (σr) and squareness ratio (S) for each sample were calculated. The maximum value of coercivity (5087Oe) was found for x = 0 wt% at T = 950 °C which is suitable for magnetic applications, such as the recording equipment and permanent magnets.