Thermogravimetry in a Gradient Magnetic Field as an Efficient Quasi In Situ Method for Studying Magnetic Phase Formation: The Case of Fe-Si-O Xerogels

In this study, we propose a fundamental methodology for the semi-quantitative analysis of magnetic phase composition during thermogravimetry in a gradient magnetic field, particularly in cycling mode. This approach is exemplified using Fe-Si-O xerogels, where magnetic nanophases such as γ-, α-, and ε-Fe₂O₃ coexist. We present a novel, time-efficient quasi in situ technique for identifying and optimizing annealing conditions to achieve single-phase ε-Fe₂O₃, a material of high industrial relevance. This work establishes a valuable framework for advancing the controlled synthesis of magnetic compounds.