Structural and magnetic properties of TbxY3−xFe5O12 (0 ≤ x ≤ 0.8) thin film prepared via sol–gel method

Terbium-doped yttrium iron garnet (TbxY3−x Fe5O12; x = 0.0, 0.2, 0.4, 0.6 and 0.8) nanoparticles thin films have been prepared onto quartz substrate by sol–gel method followed by spin coating process. Annealing of the films was processed at 900 °C in air for 2 h. The structures were investigated by using an X-ray diffractometer (XRD) and a field emission scanning electron microscope (FE-SEM). The magnetic properties were studied by a vibrating sample magnetometer (VSM). The XRD patterns of the films were consistent with a single phase garnet structure. The lattice parameter was initially increased with Tb3+ concentration due to the larger size of the Tb3+ ion compared to Y3+ ion, but a decrease in lattice parameter was observed at higher Tb3+ concentration due to the effect of film’s thickness. FE-SEM micrographs reveal that the particles were highly agglomerated. The grain’s sizes for all films were in the range of 40–59 nm. The magnetic measurements at room temperature (25 °C) show that the saturation magnetization (Ms) of the films was reduced with the increase in Tb3+ ions, which due to the antiparallel alignment between Tb3+ ions and Fe3+ ions. The films illustrate normal shapes of hysteresis loops except Tb0.2Y2.8Fe5O12 and Tb0.4Y2.6Fe5O12 films exhibiting two steps increments before being saturated. The coercivity values (Hc) demonstrate non linear dependency with the terbium concentration (x).