Structural and magnetic study of Tb$^{3+}$ doped zinc ferrite by sol-gel auto-combustion technique

In this study, the influence of Tb$^{3+}$ substitution in zinc ferrite is reported. ZnTb$_x$Fe$_{(2-x)}$O$_4$ ($x$ = 0, 0.025, 0.05, 0.075, 0.1, 0.125, and 0.15) were prepared using sol-gel auto-combustion technique. All the samples were sintered at 400$^\circ$C for 4 hours. The structure has been studied using XRD, FTIR, UV-visible, and VSM. X-ray diffraction evaluation demonstrates formation of spinel ferrite with nano size distribution. Vibrating sample magnetometer was used to study the magnetic properties of the samples. It was found that as terbium content increases, the coercive field decreases while the saturation magnetization increases. The Tb$^{3+}$ doped nanocrystalline zinc ferrites show ferrimagnetic behavior. FTIR analysis show the presence of two expected bands attributed to tetrahedral and octahedral metal oxygen vibrations at 320 and 450 cm$^{-1}$.