Tellurite And Fluorotellurite Glasses For Active And Passive

9. Conclusions; MDO 383
due to the change in the chemical environment surrounding the erbium (III) ion,
possibly due to preferentially segregation of Er +3 to the crystallites.
Refractive indices
• PbO addition to TeO2-Na2O-ZnO glasses resulted in an increase in refractive
index, and GeO2 caused a decrease, due to the high and low polarisability
respectively compared to TeO2 [13].
• TeO2 glasses which contained WO3, Bi2O3, and Nb2O5 had higher refractive
indices than the TeO2-Na2O-ZnO glasses, due to the high polarisability of all
components [13].
• Refractive index of the series (90-x)TeO2-10Na2O-xZnF2, mol. %, 5 ≤ x ≤ 30 mol.
% decreased linearly with ZnF2 addition, from 2.02 (x = 5 mol. %) to 1.85 (x = 30
mol. %), as the fluoride and zinc are less polarisable than oxygen and tellurium
[6].
• Glasses in the series 65TeO2-(25-x)ZnF2-xZnO-10Na2O mol. %, for 5 ≤ x ≤ 25
mol. % showed a linear increase refractive index with oxide / fluoride ratio, from
1.887 (ZnO / ZnF2 = 0) to 1.952 (ZnO / ZnF2 = 1).
Core / clad choice
• For the series (90-x)TeO2-10Na2O-xZnF2, mol. %, 5 ≤ x ≤ 30 mol. %, stable
glasses can be formed (Tx-Tg > 110°C), with only a small shift in the multiphonon