Tellurite And Fluorotellurite Glasses For Active And Passive

4. Thermal properties and glass stability; MDO 109
It can be seen from these curves that the glass transition temperature increases as the
molar ratio of ZnO to ZnF2 increases. Fig. (4.18) illustrates this trend along with Tx and
Tx-Tg. Data for glass MOF001: 65TeO2-10Na2O-25ZnF2 (ZnO:ZnF2 = 0 = x) was added
to this figure.
Temperature / o C
450
400
250
200
150
100
0.0 0.2 0.4 0.6 0.8 1.0
ZnO / ZnF 2 ratio
T x
T g
T x -T g
Fig. (4.18): Variation in Tg, Tx and Tx-Tg with ZnO / ZnF2 ratio for series 65TeO2.(25x)ZnO.xZnF2.10Na2O
(mol. %), for 0 ≤ x ≤ 20 from fig. (4.17).
The irregular trend which Tx and Tx-Tg exhibit is likely to be due to an underlying
structural change or two opposing effects in the glass.