Tellurite And Fluorotellurite Glasses For Active And Passive

6. Optical properties; MDO 231
Scholze [17] identified a band around 2350 cm -1 for alkali metal silicate glasses and
assigned this to the stretching mode of Si-OH groups which form the strongest hydrogen
bonding with the NBO’s of the isolated SiO4 tetrahedron Q 0 (i.e. isolated SiO4 group with
no bridging oxygens). Ryskin [22, 23] also identified a band attributed to a stretching
mode of the hydrogen-bonded Si-OH groups around 2350 cm -1 for crystalline hydrated
silicates. It is proposed that the band, which occurs around 2290 cm -1 for tellurite glasses
(fig. (6.17)) be attributed to the stretching mode of the strongly hydrogen-bonded Te-OH
groups [5].
Ryskin [22, 23] identified a band at circa 1700 cm -1 attributed to a stretching mode of
the hydrogen-bonded Si-OH groups and band at circa 1650 cm -1 assigned to the bending
mode of the water molecule in crystalline hydrated silicates. However, this former band
would contradict Scholze [17] who stated the strongest hydrogen bonded Si-OH
stretching band for multi-component silicate glasses occurs around 2350 cm -1 , meaning
there are no more stretching modes for hydrogen-bonded R-OH groups at lower
wavenumbers than 2350 cm -1 . Bands around 1650 and 1700 cm -1 were not seen in this
study.
Fuxi [24] has reported Raman or infrared active fundamental lattice vibrations of
tellurite glasses. Fuxi [24] identified the fundamental symmetric stretch of O-Te-O at 790
cm -1 . It is propose that the band which occurs around 1550 cm -1 in fig. (6.14) corresponds
to the first overtone of the 790 cm -1 fundamental (2 × 790 cm -1 = 1580 cm -1 ) or the
bending mode of molecular water identified by Ryskin (or a convolution of both) [5].
Fuxi [24] identified the fundamental asymmetric stretch of O-Te-O or Te-O - at 710
cm -1 and the group vibration of [TeO6] at 610 cm -1 . It is proposed that the band which