Synthesis and magnetic properties of the SiO2–BaFe12O19 glass–ceramic composites

Samples of the magnetic glass–ceramics SiO2–BaFe12O19 were obtained from mixtures of Fe2O3–BaSO4–SiO2–Na2CO3–CaCO3 following a two-step route. The samples were characterized using XRD analysis and scanning electron microscopy, and their room temperature magnetization hysteresis loops were measured. It was found that the magnetic phase was completely developed in the precursor BaFe12O19 material when it was calcinated above 1000 °C. The size of the particles of the BaFe12O19 phase depends on the thermal treatment conditions and on the SiO2 concentration. The magnetic data showed that the high value of the coercive magnetic field is preserved despite the fact that both the remanent and the saturation magnetizations diminish substantially.