The investigation was made concerning the dependence of transformation temperatures, softening temperatures and thermal expansion coefficients of Si-As-Te glasses on composition. Transformation temperatures,
Tg, are in the range from about 110 to 368°C, and increase with increasing silicon content and decrease with increasing tellurium content. Temperatures of initial deformation under load, i.e., softening temperatures,
Ts, are within about 125 to 425°C and exhibit the same dependence on composition as in the case of
Tg. Average linear thermal expansion coefficients at temperatures from room temperature to
Tg, α
l and from
Tg to
Ts, α
h, are in the range (0.8-2.1)×10
-5cm/cm/°C and (1.3-6.2) 10
-5cm/cm/°C, respectively. In contrast to the dependence of
Tg and
Ts on composition, α
l and α
h decrease with increasing silicon content and increase with increasing tellurium content. For the glasses of a given atomic ratio of silicon to arsenic, both
Tg and
Ts increase linealy with increasing the concentration of covalent bonds per unit volume, [
v], and the following relations are obtained:
When the (Si/As) atomic ration is 1.50,
Tg=97.19[
v]×10
2-441.4,
Ts=112.06[
v]×10
2-506.3.
When the (Si/As) atomic ratio is 0.67,
Tg=78.49[
v]×10
2-350.6,
Ts=84.85[
v]×10
2-368.6.
When the (Si/As) atomic ratio is 0.25,
Tg=51.61[
v]×10
2-201.1,
Ts=60.14[
v]×10
2-237.8.
The values of [
v] in this investigation are in the range from 5.79×10
-2 to 8.32×10
-2 mole/cm
3. Thermal expansion coefficients, α
l and α
h, decrease linearly with increasing the concentration of covalent bonds, regardless of the (Si/As) atomic ratio α
l×10
5=-0.4725[
v]×10
2+4.826,
α
h×10
5=-1.4976[
v]×10
2+14.616.
From the above relations, the following values are estimated for amorphous tellurium:
Tg=35±4°C,
Ts=43±3°C,
α
l=(2.54±0.13)×10
-5cm/cm/°C and α
h=(7.38±0.28)×10
-5cm/cm/°C.
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