Investigation of the effective parameters on the synthesis of strontium hexaferrite nanoparticles by chemical coprecipitation method

Abstract

Strontium hexaferrite nanoparticles were synthesized by chemical coprecipitation method in the presence of polyvinylpyrrolidone (PVP) as a protective agent. A mixture of the deionized water/ethanol (50/50) was used as the solvent. The effects of PVP, pH of the solution, Fe3+/Sr2+ molar ratio and calcination temperature of the precipitates on the synthesis of strontium hexaferrite samples were studied. X-ray diffraction (XRD), scanning electron microscope (SEM), thermal analysis (DTA–TGA), dynamic light scattering particle size analyzer (PSA) and vibrating sample magnetometer (VSM) were used to investigate the properties of the obtained samples. The results showed that increasing the pH from 9 to 13 or decreasing Fe3+/Sr2+ molar ratio from 12 to 9 promoted SrFe12O19 formation and decreased the size of nanoparticles. The minimum coercivity of 4733Oe and maximum saturation magnetization of 51emu/g were obtained by increasing the pH from 9 to 13. It was also concluded that PVP could be effective in decreasing the size of SrFe12O19 nanoparticles and resulted to decrease the calcination temperature from 800 to 700°C.