Investigation and synthesis of Fe doped Al_2 O_3 nanoparticles by Co-precipitation and sol gel methods

This study doped alumina with iron impurities by co-precipitation and sol-gel methods compared with pure alumina. Precursors of aluminum and iron metal salts employ the surfactant and new stabilizers used for synthesizing samples. Several analysewere performed on different properties of the synthesized samples and the effect of iron impurities on them. The presence of different phases was confirmed in the XRD spectrum of nanoparticles made by co-precipitate method. As the percentage of impurities increases, the unstable and intermediate phases decrease and eventually tend to the stable phase of α-alumina, the resulting hexagonal structure is obtained. The FESEM spectra of samples synthesized by both methods showed that a decrease in particle size occurs with an increase in the percentage of impurities. TEM analysis of nanoparticles with 5% impurity shows the shape of the particles as quasi-spherical, about agglomerate. It is the reason for removing the stabilizing agent in the high-temperature heating process. Also, increasing the intermolecular gravitation force, the particles stick together in a lump. UV-DSR analysis showed that with increasing impurity percentage, the energy band gap decreases and the absorption wavelength  increases. In samples fabricated in both methods, the value of  obtained is close to each other. The VSM spectrum showed that ferromagnetic properties occur when iron enters alumina sites.