Abstract
Ferrimagnetic bulk glass-ceramics and glass fibers containing magnetite crystals in the system SiO2–Al2O3–Fe2O3–B2O3–CaO–MgO–ZnO were prepared via different fabrication methods. The X-ray diffraction, scanning and transmission electron microscopy, vibrating sample magnetometer, electromagnetic parameters, Mössbauer spectra and calorimetric measurements were employed to characterize structure and detect performance of the samples. The estimated size of the spontaneous crystallized magnetite is about 30 nm. The influence of intermediate oxide alumina substituting for network former oxide silica on the spontaneous crystallization of magnetite in glass was investigated. Our results indicated that the ability of magnetite spontaneous crystallization without performing nucleation and crystallization heat treatments was dependent on the chemical composition and fabrication methods.
