Mechanical and optical properties of the chalcogenide glass system As2Se3-xTex

Chalcogenide glasses of As
2
Se
3-x
Te
x
(
0 \leq x \leq 3
) were fabricated with special care to avoid traces of oxygen, using very pure raw materials. From part of these materials, special plates were made, and from the rest fibers were pulled. From transmittance measurements, the existence of absorption bands was shown, corresponding to the presence of small crystallites of As
2
O
3
. The attenuation in the infrared of these plates increased from 14 dB/m for As
2
Se
3
to 29 dB/m for As
2
Se
0.5
Te
2.5
. Conversely, a decrease of microhardness V
H
was observed. The attenuation of CO
2
laser light (
\lambda = 10.6 \mu
m) transmitted through the pulled fibers was measured as a function of the Te(
x
) content. and an increase of the attenuation was observed from 18.1 dB/m for As
2
Se
3
to 66.7 dB/m for As
5
Se
1.5
Te
1.5
. The surface of each fiber was examined in the scanning electron microscope and an increase of the defects (e.g., crystallites) when the Te content was increased, was observed. These defects (crystallites) are the main factors for finding an increase in the absorption in IR.