Crystallization Process and Magnetic Properties of Amorphous ${rm NiFe}_{2}{rm O}_{4}$ Nanoparticles

摘要

We investigate the crystallization process of ${rm NiFe}_{2}{rm O}_{4}$ nanoparticles prepared by microwave heating technique, which were then characterized using X-ray diffraction, high-resolution transmission electron microscopy, the differential scanning calorimetry, Raman scattering, Fourier transformed infrared spectra (FTIR), and magnetic measurements. The results showed that crystallization of the amorphous ${rm NiFe}_{2}{rm O}_{4}$ nanoparticles occurred at around 300 $^{circ}{rm C}$ . The best crystallization quality would be obtained by annealing the sample at 500 $^{circ}{rm C}$ . After crystallization, the sample shows ferromagnetic behavior with a saturation magnetization of about 30 emu/g. The FTIR and Raman measurements also provided further information about the crystallization process and the phase transformation of the ${rm NiFe}_{2}{rm O}_{4}$ nanoparticles.