Structural and redox effects in iron-doped magnesium aluminosilicates

Magnesium aluminosilicates (MAS) represent a great importance for many electrical and catalytic applications. Recently, MAS-based glasses were considered as prospective for use as an electrolyte in steel making by molten oxide electrolysis process, an alternative electrometallurgical technique which offers prospects for environmental and economic advantages over traditional steelmaking. In the present work, low-iron content MAS glasses were processed by an unconventional method: the laser floating zone (LFZ), to simulate the strongly-nonequilibrium high-temperature conditions which may arise during pyroelectrolysis process. The work focuses on the effect of pulling rate on crystallization kinetics, taking into account structural, electrical and magnetic properties of the as-grown material. The results revealed that faster pulling rates promote formation of isolated iron cations in the glass forming network. The crystallization process is strongly affected by lower pulling rates. LFZ method shows good prospects for studying the crystallization mechanisms in silicate-based glasses with additions of redox-active cations, by providing flexibility in tuning their oxidation state and crystalline/amorphous conditions. •LFZ used for study crystallization behavior in iron-doped MAS glass system.•Pulling rate is a crucial parameter for a non-magnetic phase precipitation.•Pulling rates above 100mm/h lead to amorphous material.•Lower pulling rate results in an increase of sample crystallinity.•Pulling rate influence oxidation state of iron and the interaction with matrix.