From volcanic ashes to magnetic zeolites: unravelling the iron oxide phase transitions by magnetic and advanced structural characterization

Volcanic ashes, rich in iron-containing phases, present an underexplored resource for creating functional materials. In this study, we investigate the hydrothermal transformation of volcanic ashes from Mount Etna (Sicily, Italy) into magnetic zeolites, exploring both structural and magnetic evolution. By combining X-ray absorption spectroscopy (Fe K-edge) and magnetometry, we reveal how the phase transition from olivine to magnetite-like phases, and hematite influences the magnetic behaviour. We observe distinct changes in iron oxidation states, coordination, and the emergence of antiferromagnetic contributions. This work highlights the potential of volcanic ashes as a sustainable source for designing advanced materials with tunable magnetic properties.