Study on Magnetic Properties of Dy0.15Fe1.85O3 Magnetic Nanoparticles at Low Temperature

Dy0.15Fe1.85O3 magnetic nanoparticles were prepared by coprecipitation-phase transfer method, and the effect of temperature variation on the magnetic properties of the nanoparticles at low temperature were investigated. The chemical composition, morphology, crystalline structure and magnetic properties of the samples at low temperature were characterized by X-ray fluorescence spectrometer(XRF), transmission electron microscope (TEM), X-ray diffraction (XRD) and super-conducting quantum magnetometer (SQUID). The results show that metal ions in the sample are mainly Dy3+ and Fe3+ whose mass fractions are 12.17% and 51.88%, respectively. The average diameter of the samples is ca. 15 nm. The magnetic particles are spherical with face-centered cubic spinel structure and complete crystalline. The saturation magnetization (MS) and coercivity (HC) of the samples increase with the decrease of temperature in the range of 56.5 K and 200.2 K. When the temperature exceeds or is equal to 142.8 K, the magnetic properties of the samples is at the superparamagnetic state. While the temperature is below 142.8 K, the superparamagnetic state is converted to ferromagnetic state.