Effect of annealing temperature on structural and magnetic properties of BaFe12O19 hexaferrite nanoparticles

In the present work, barium hexaferrite nanoparticles were synthesized through a co-precipitation route in the presence of a high concentration hydroxide ion at low temperature. Effect of annealing temperature on structure, morphology and magnetic properties of nanoparticles was investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM). XRD patterns of the samples along with FTIR analysis confirmed the formation of crystalline hexagonal ferrite phase for powders annealed above 700 °C. Also, the FE-SEM images showed that particle size increased from few nanometers to micrometers by increasing annealing temperature from 90 to 1200 °C. Moreover, the VSM results indicated that, with increasing annealing temperature, magnetization and coercivity increased and reached maximum value of 46 emu g−1 and 5278 Oe, respectively, for the sample annealed at 900 °C. Also, the low-temperature (90 °C and 500 °C) annealed samples were superparamagnetic in nature at room temperature due to their near-zero coercivity and remanence.