Preparation of magnetic glass-ceramics by crystallization of ternary eutectic Li2O-MgO-SiO2 system reformed with some di-and trivalent oxides

摘要

This work sheds light on influence of replacing MgO by SrO, MnO or Fe2O3 on the crystallization and magnetic properties of glass-ceramics based on the ternary Li2O-MgO-SiO2 eutectic (935 +/- 10 degrees C) system. Moreover, the effect of adding Al2O3 was also studied. All the glass samples were prepared by the conventional melting technique. Magnetic hysteresis cycles were analyzed using a vibrating sample magnetometer with applied magnetic field up to 20 kOe at room temperature. The bulk density and Vicker microhardness were also evaluated. The crystalline phases formed are lithium meta- and di-silicate, MgSiO3, SrSiO3, Sr-akermanite (Sr2MgSi2O7), beta-MnSiO3 and four crystalline phases of pyroxene type like Kanoite-MgMnSi2O6, beta-spodumene and Li-aegirine (LiFeSi2O6) with its solid solution (Li,Mg)FeSi2O6. Spinel-LiFe5O8 magnetic phase was also detected. The density values of the examined glass-ceramics are between 2.48 and 2.91 g/cm(3). A dense fine microstructure provides superior hardness glass-ceramics up to 6523 MPa is also obtained. The obtained magnetization data is mainly related to the nature of crystalline phases formed and the resulting microstructure. The results reveal an improvement in the magnetization and mechanical properties which render the prepared glass-ceramics useful for hyperthermia treatment of cancer-like bone tumors and for electronic devices as magnetic disk substrates.