Tellurite And Fluorotellurite Glasses For Active And Passive

6. Optical properties; MDO 184
Absorption coefficient / cm -1
2.00
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0.00
Multiphonon
edge
Strong
OH band
CH / CH 2 / CH 3
doublet
Combination band of
weak and free OH
Wavelength / µm
6 5 4 3 2
Envelope of
atmospheric OH
rotational bands
(80-x)TeO -10ZnO-10Na O-xMO
2 2
MOD006 (x =3 mol. % PbO)
MOD010 (x =5 mol. % PbO)
MOD012 (x = 5 mol. % GeO ) 2
1st overtone of
strong OH band
2000 3000 4000 5000 6000
Wavenumber / cm -1
OH and CH
overtone and
combination
band region
Fig. (6.6): Infrared spectra of glasses in the series (80-x)TeO2-10Na2O-10ZnO-xMO,
where MO is PbO or GeO2, for MOD006 (x = 3 mol. % PbO), MOD010 (x = 5 mol. %
PbO) and MOD012 (x = 5 mol. % GeO2). Strongly hydrogen bonded OH = strong OH
and weakly hydrogen bonded OH = weak OH.
It can be seen the multiphonon edge (taken from the x-axis where the absorption
coefficient reaches 2 cm -1 ) for these glasses occurred at around 1667 cm -1 (6 µm). All
three glasses exhibited absorption bands in the infrared region due to hydroxide (OH)
groups in the glass. Three OH bands were seen, the positions depending on the degree of
hydrogen bonding of the OH in the glass: strongly hydrogen bonded OH (strong OH),
weakly hydrogen bonded OH (weak OH), and free OH. A higher intensity asymmetric
band was seen at around 3000 cm -1 (3.33 µm). This band was identified as a combination
band of weakly H-bonded OH and free OH. The lower intensity band at around 2270
cm -1 (4.41 µm) was due to strongly H-bonded OH in the glass. The doublet which
appeared at around 2800 cm -1 (3.57 µm) for glass MOD010 was identified as CH / CH2 /
2000
1750
1500
1250
1000
750
500
250
0
Loss / dB.m -1