Magnetic properties of YIG doped with cerium and gadolinium ions

Nanoparticles Y_3−x−y Ce _x Gd _y Fe₅O₁₂ (x = 0–0.1, y = 0–1.0) were fabricated by a sol–gel method. The crystalline structures and magnetic properties of samples were investigated by X-ray diffraction (XRD), scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM). The XRD patterns of Y_3−x−y Ce _x Dy _y Fe₅O₁₂ have only peaks of the garnet structure and the mean size range from 42 nm to 65 nm. The particle’s size observed for all the samples analyzed by SPM are in good agreement with these data from XRD. The particle’s size ranged from 50 nm to 70 nm, at the same time, there are small amount of reunited particles can be observed. XPS for Y_2.9Ce_0.1Fe₅O₁₂ gives two peaks at 885.15 and 905.15 eV attributing to Ce³⁺ 3d^5/2 and 3d^3/2, respectively. The results confirm the valence state of Ce atoms being +3. Results of VSM show that the saturation magnetization is increased with increasing Ce content (x) and is decreased with increasing the Gd concentration (y) in a linear manner. The saturation magnetization is increased with increasing the particle’s size.