Tellurite And Fluorotellurite Glasses For Active And Passive

6. Optical properties; MDO 232
occurs at 1370 cm -1 in fig. (6.14) be attributed to the combination of these two
fundamental bands (730 + 610 = 1340 cm -1 ) [5]. The current author would assign the
band which occurs at 1210 cm -1 in fig. (6.14) to the first overtone of the aforementioned
610 cm -1 band due to the vibration of the [TeO6] group (2 × 610 cm -1 = 1220 cm -1 ). The
band which occurs at 1070 cm -1 in fig. (6.14) could be attributed to the first overtone of
the [TeO6] band at 490 cm -1 (2 × 490 cm -1 = 980 cm -1 ), however this is unlikely as the
fundamental absorption is weak (and the overtone would be even weaker) and the
difference between theoretical and experimental band positions is too large (90 cm -1 ) [5].
The assignment of these bands is summarised in table (6.13) below.
Table (6.13): Assignment of absorption bands from fig. (6.14) and (6.15) for a 0.2 mm
sample of glass MOD013: 80TeO2-10Na2O-10ZnO (mol. %) [5].
Band / cm -1 Comments Ref.
≈ 3300
Stretching mode of free Te-OH groups and/or
stretching mode of molecular water
[14, 17, 22,
23]
≈ 3060
Stretching mode of weak hydrogen-bonded Te-
OH groups
[17, 22, 23]
≈ 2290
Stretching mode of strong hydrogen-bonded
Te-OH groups
1
[17, 22, 23]
≈ 1550
st overtone of O-Te-O symmetric stretch (2 ×
790 = 1580 cm -1 ) and/or bending mode of
molecular water
Combination of asymmetric stretch of O-Te-O
[14, 22-24]
≈ 1370 or Te-O - and [TeO6] group vibration (730 +
610 = 1340 cm -1 )
[24]
≈ 1210
1 st overtone of [TeO6] group (2 × 610 = 1220
cm -1 )
[24]
≈ 1070
Unidentified, possibly 1 st overtone of [TeO6]
group vibration (2 × 490 = 980 cm -1 )
[24]
The proposed identification of the multiphonon absorption bands shown in table (6.13)
assumed that combination bands and overtones of fundamental Raman and infrared Te-O