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

Highlights: ► SrFe12O19 nanoparticles with 25 nm were obtained using EG assisted hydrothermal method. ► SrFe12O19 nanoparticles were modified by oleic acid to form stable magnetic fluid. ► The magnetic fluid had obvious heating effect in an alternating magnetic field. -- Abstract: Strontium hexaferrite (SrFe12O19) 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 SrFe12O19 nanoparticles. SrFe12O19 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, SrFe12O19 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