Tellurite And Fluorotellurite Glasses For Active And Passive

9. Conclusions; MDO 382
• For fibre drawing, the TeO2-Na2O-ZnO glasses would be more suitable than the
tungsten-tellurite compositions, as they can be worked at lower temperatures (Tg ≈
280 and 350°C respectively), and transmit further into the infrared (≈ 6 and 5.25
µm respectively), even though OH bands were more intense, which could be
potentially reduced with reactive atmosphere processing (RAP).
• For the series (90-x)TeO2-10Na2O-xZnF2, mol. %, 5 ≤ x ≤ 30 mol. % melted for 2
hours, OH bands at 2900 cm -1 were reduced in intensity with ZnF2 addition due to
self drying of the melt, from around 120 dB.m -1 (x = 5 mol. %) to 20 dB.m -1 (x ≥
15 mol. %) [6].
• Melting time also had a significant effect on drying of this series, with the loss at
2900 cm -1 reduced by two orders of magnitude when increased from 1 hour (705
dB.m -1 ) to 2 hours (10 dB.m -1 ) [6].
• The OH bands of this series did not exhibit strongly-hydrogen bonded OH,
possibly obscured by the multiphonon edge, or more likely, very little was present
due to the low OH content of the glass, resulting in weakly hydrogen-bonded OH
and free OH statistically and energetically more favourable, however -F-----HO-
type bonds will exist.
• The 65TeO2-(25-x)ZnF2-xZnO-10Na2O mol. %, 5 ≤ x ≤ 25 mol. % glasses
showed an increase in OH bands with molar ZnO:ZnF2 ratio, and again the ZnF2
containing glasses did not exhibit strongly-hydrogen bonded OH bands.
• Glass 69.86TeO2-9.98Na2O-19.96ZnF2-0.20ErF3 mol. % was heat treated, with
varying times and temperatures above Tg, and enhancement of the Er +3 bands in
the visible and near-IR was seen with increasing treatment. This is likely to be