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

We investigate the crystallization process of NiFe
₂
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 NiFe
₂
O
₄
nanoparticles occurred at around 300 °C. The best crystallization quality would be obtained by annealing the sample at 500 °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 NiFe
₂
O
₄
nanoparticles.