Glass formation and immiscibility in the TeO2-B2O3-Fe2O3-MnO system

The glass formation in the quaternary TeO₂-B₂O₃-MnO-Fe₂O₃ system and in its ternary systems was investigated. A range of liquid immiscible phases, located near to the binary TeO₂-B₂O₃ and B₂O₃-MnO systems was established. Using transmission electron microscopy, a trend to metastable liquid-phase separation in the single-phase glasses, located near to the boundary of immiscibility was observed. With an increase in the Fe₂O₃ and MnO content still in the process of cooling of the melts, it was possible for a fine glassy crystalline structure to be formed in them. It was shown that by changing the upper limit of the melting temperature and the cooling rate, the glassy crystalline structure and the Fe₃O₄ content could be modified.