Comprehensive study of Ni-substitution yttrium iron garnet impact of substitution levels annealing temperature on structural and magnetic properties

This study aimed to determine the optimal annealing temperature and Ni2+ substitution level to enhance the magnetic properties of YIG films. Nickel-substitution yttrium iron garnet (Y3Fe5-xNixO12; x = 0.03, 0.05, 0.07, and 0.09) films have successfully been prepared onto quartz substrate by a sol-gel method followed by a spin-coating technique. The films were annealed at 700 degrees C, 800 degrees C, and 900 degrees C in air for 2 h. Microstructure studies using an X-ray diffractometer confirmed that the films exhibit a pure garnet phase at 900 degrees C. A slight increase in the lattice parameter was noticed at lower Ni2+ concentrations (x = 0.03), followed by a linear increase at higher concentrations, indicating a complete incorporation of Ni2+ into the YIG structure. The film morphology observed using a field emission scanning electron microscope shows that the film particles were highly agglomerated. The film thickness ranges from 120 nm to 170 nm and shows good adhesion to the quartz substrate. The magnetic properties were studied using a vibrating sample magnetometer. Regardless of the substitution value, both saturation (Ms) and remanent magnetization (Mr) increased with annealing temperature. However, coercivity exhibited an unsystematic trend with the temperature. In contrast, the effect of substitution on magnetic properties showed a completely different pattern. The used of Ni2+ substitution to enhance saturation and remanent magnetization, appears to have a limitation, with the highest values of Ms and Mr observed at x = 0.07. Nevertheless, coercivity varied inconsistently with substitution levels. These findings suggest that the structural and magnetic characteristics of Y3Fe5O12 garnets can be fine-tuned through Ni2+ substitution at different annealing temperatures, making them promising for various technological applications.