Tellurite And Fluorotellurite Glasses For Active And Passive

9. Conclusions; MDO 380
9.3. Optical properties (Chapter 6)
Infrared spectroscopy
• Infrared spectra of oxide tellurite and fluorotellurite glasses were studied, and
refractive indices obtained by ellipsometry.
• Addition of PbO and GeO2 to TeO2-Na2O-ZnO glasses shifts the multiphonon
edge (at ≈ 6 µm) to lower and higher wavenumbers respectively, due to bond
strength and the masses of the cations (as predicted by the Szigeti equation [10]).
• Addition of ZnO to TeO2-Na2O-ZnO compositions shifts the multiphonon edge to
higher wavenumbers.
• A number of absorption bands in the infrared were identified in the TeO2-Na2O-
ZnO glasses due to intrinsic lattice vibrations (visible in a 0.2 mm sample), and
extrinsic impurities [6]:
o Free OH / molecular water stretching mode (≈ 3.0 µm ≡ 3300 cm -1 ).
o Weakly hydrogen-bonded OH stretching mode (≈ 3.3 µm ≡ 3060 cm -1 ).
o Strongly hydrogen-bonded OH stretching mode (≈ 4.8 µm ≡ 2090 cm -1 ).
o 1 st overtone of O-Te-O symmetric stretch / bending mode of molecular
water (≈ 6.5 µm ≡ 1550 cm -1 ).
o Combination of asymmetric stretch of O-Te-O or Te-O - and [TeO6] group
vibration (≈ 7.3 µm ≡ 1370 cm -1 ).
o 1 st overtone of [TeO6] group (≈ 8.3 µm ≡ 1210 cm -1 ).