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

Abstract

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.