Ethylene glycol assisted hydrothermal synthesis of strontium hexaferrite nanoparticles as precursor of magnetic fluid

Abstract Strontium hexaferrite (SrFe 12 O 19 ) nanoparticles were prepared using ethylene glycol (EG) assisted hydrothermal synthesis. The experimental results revealed that the reaction temperature and the amount of EG had an effect on the size, morphology and magnetic properties of SrFe 12 O 19 nanoparticles. SrFe 12 O 19 nanoparticles with a size of about 25 nm were obtained at 140 °C for 24 h at the EG/W volumetric ratios of 1/1. The saturation magnetization of the particles was approximately 10.6 emu/g. Furthermore, SrFe 12 O 19 nanoparticles modified by oleic acid could be dispersed in high boiling point mineral oil to form highly-concentrated magnetic fluid. The magnetic and rheological properties of magnetic fluid were investigated using a Gouy magnetic balance and a rotational rheometer, respectively. The magnetic fluid showed excellent stability in gravity field and external magnetic field, and exhibited shear-thinning behavior. Moreover, the magnetic fluid had obvious heating effect in an alternating magnetic field and had potential on hyperthermia therapy of tumor.