Effect of heat treatment atmosphere on the formed phases in magnetite glass ceramic in SiO2-B2O3-Fe2O3-Na2O-ZnO system

In this study، the glass with SiO2-B2O3-Fe2O3-Na2O-ZnO systemwas set in the various atmosphere ofhydrogen reducing، nitriding ammonia gas and neutral argon gas and also graphite-bed at 590 ̊C for 1 h and the effect of the formed phases during crystallization of the magnetite and also the magnetic characteristics of the magnetite glass-ceramic were investigated. The characterization of the phases was carried out by X-ray diffraction and the magnetic properties were studied by vibrating sample magnetometer (VSM). The magnetite phase was formed in the heat treated samples in graphite-bed and argon atmosphere and saturation magnetization of the primary glass was measured 19 emu g-1 in both samples. After the heat treatment of the glass in reducing atmosphere، magnetic phases of magnetite and α-Fe were detected in X-ray diffraction pattern. The existence of α-Fe was resulted in the improvement of the magnetic properties and also the increase in the saturation magnetization to 27 emu g-1. In The heat treated glass in ammonia gas atmosphere، there was no iron nitride phase and just the magnetite phase was crystallized. The saturation magnetization of this sample was estimated to 18. 3 emu g-1.