Impact of the pulling rate on the redox state and magnetic domains of Fe-Si-O glass ceramic processed by LFZ method

This work studies the effect of the pulling rate, varying from 100 to 400 mm/h, on the redox state, structure and magnetic properties of iron oxide bearing silica glasses processed by laser floating zone (LFZ) method. XRD analysis revealed that the maximum crystallinity is obtained in the fibre grown at the lowest pulling rate. A detailed Raman analysis demonstrated that the global content of Fe2+ increases with pulling rate, while the growth under a lower pulling rate promotes the alpha-Fe2O3 crystallization. Atomic/magnetic force microscopy provided further evidence of phase-separated iron oxide crystallites formation with a high Fe2+/F-total ratio as the pulling rate increases. The magnetic measurements performed over a wide temperature range showed that the highest magnetization is found in the fibre grown at the highest pulling rate. A strong correlation between structural-topographical features and the magnetic characteristics of the glass fibres is substantiated.