Formation and properties of erbium aluminoborate glasses

The glass forming region, densities, thermal expansion coefficients and glass transformation and dilatometric softening temperatures have been determined for erbium aluminoborate glasses. Densities and thermal expansion coefficients increase with increasing Er2O3 concentration, while the glass transformation temperature is almost independent of Er2O3 concentration. The glass transformation and dilatometric softening temperatures, which are exceptionally high for borate glasses, are primarily determined by the boric oxide concentration. Absorption bands in the infrared spectra of these glasses vary with hydroxyl concentration (3500 cm(-1) band) and with boric oxide content (bands at 2650 and 2280 cm(-1)). The 2650 cm(-1) band position is sensitive to the concentrations of all three glass components, while the band at 2280 cm-1 is primarily determined by the boric oxide concentration. The extinction coefficient for the band due to Er2O3 in the visible spectra at 650 nm is 2(.)73 l/mol cm.