dMagnetic properties of B2O3-SiO2-BaO-Fe2O3 glass-ceramics

The magnetic characterization of B2O3-SiO2-BaO-Fe2O3 glass-ceramics during annealing process was the goal of this study. In this regard, different mixtures of BaO, Fe2O3, SiO2 and B2O3 were melted and then quenched between two cold steel sheets. The annealing process was done in as-quenched samples in temperature range of 550 to 850 degrees C for different periods of time. The prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and vibrating scanning magnetometer (VSM). According to achieved results, fully amorphous structure can only be formed in 20B(2)O(3)-10SiO(2)-45BaO-25Fe(2)O(3) system and the microstructures of as-quenched samples in other systems were combination of Fe3O4, BaFe12O19 and amorphous phases. The coercivity and saturation of magnetization of as-quenched samples were estimated about 85-120 Oe and 12-17 emu/g, respectively. By annealing the produced samples, the coercivity value was increased to about 3100 Oe as a result of precipitation of BaFe12O19 in nonmagnetic Ba2FeSi2O7 matrix. The highest value of coercivity was achieved in annealed sample at 700 degrees C for 5 h. (C) 2016 Elsevier B.V. All rights reserved.