Research on glass forming ability of Er₂O₃ - Al₂O₃-B₂O₃ - SiO₂ System

The glass forming range of Er₂O₃ - Al₂O₃-B₂O₃ - SiO₂ system was explored, and the effect of the content of Al₂O₃ and Er₂O₃ on glass-forming region was experimentally examined. It is shown that the region of glass formation range expends when the content of Al₂O₃ is changed from 15% to 20%, while it shrinks when the content of Er₂O₃ is changed from 20% to 30%. At the same time, the glass forming ability of Er₂O₃-Al₂O₃ - B₂O₃-SiO₂ system was also discussed using a value of β, which is an indication of crystallization tendency of glasses, calculated from thermo-analysis data. It is found that the glass forming ability of Er₂O₃ - Al₂O₃ - B₂O₃-SiO₂ glasses is poor, while the glasses network may be enhanced when Al₂O₃ is added to the system, the glass forming ability being heightened. In addition, the crystallization temperatures of the rare earth glasses were determined using differential thermal analysis technique. The Er₂O₃ - Al₂O₃ - B₂O₃ - SiO₂ glass samples were heat treated at 1000, 1100 and 1260 °C respectively. The results show that it is the Er₂O₃ phase that separates out from the glasses after crystalline heat treatment, and it is tiered up in glasses, as detected through XRD and SEM. This indicates that the phase separation occurs when the glasses are heated, Er3+ being mainly distributed in the boron rich phase, then separated out from glasses, while the silicate rich phase remaining glassy state.