Sol-gel derived Tb3Fe5O12 and Y3Fe5O12 garnets: Synthesis, phase purity, micro-structure and improved design of morphology

Yttrium iron garnet (Y3Fe5O12; YIG) and terbium iron garnet (Tb3Fe5O12; TbIG) were prepared by an aqueous sol-gel method using two different complexing agents (1,2-ethanediol and glycerol). For the synthesis of Tb3Fe5O12 two different molar ratios of complexing agent (1:1 and 3:1) to the total metal ions were used. Thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) were performed to study the thermal behaviour of the prepared Y-Fe-O and Tb-Fe-O precursor gels. The effects of synthesis parameters on the garnet phase formation were studied by X-ray powder diffraction (XRD) analysis and scanning electron microscopy (SEM). Interestingly, the XRD data indicated that single-phase Y3Fe5O12 garnet can be prepared only with 1,2-ethanediol at lowest 1000 °C temperature. While Tb3Fe5O12 garnet can be obtained at lower temperatures depending on the nature and amount of complexing agent. The SEM results showed that parameters of sol-gel processing influence the morphological features of garnets considerably. For comparison, the conventional solid-state reaction method at 1000 °C was also used for the fabrication of both Y3Fe5O12 and Tb3Fe5O12 garnets.