Preparation of Dy-ferrite Ferrofluids and Magnetochemical Studies on the Superparamagnetism

摘要

This paper reports unprecedented preparation of Dy-ferrite water-based ferrofluids stabilized by polymeric surfactant PMAA. The stability of ferrofluids was characterized in terms Of the equation of criterion for the stability of ferrofluids. Magnetic susceptibility was measured with a Faraday-type Magnetic balance at different temperature and with different Magnetic field intensity. According to the Langevin function, Superparamagnetism of Dy-ferrite ferrofluids has been con- Firmed by the curves of saturation magnetization σ versus H/ T, and the blocking temperature is between 160 and 200 K.