Page 133 - Chalcogenide Glasses for Infrared Optics

110 Cha pte r F o u r

modulus E, the shear modulus G, and Poisson’s ratio ν may be calcu-
lated from the following equations:

ν = sound velocity, shear
S
ν = sound velocity, longitudinal
L 1  2 
ν= Poisson's ratio = 1 −  v S 2
2 2  v 2 − v 
L S
ρ= density
G =ρν 2 E = (1 +ν)
S
Perhaps the first application of acoustical methods to chalco genide
glasses was reported from Bell Labs by Krause et al. when they stud-
9
ied sound velocity and acoustical attenuation in TI 20 (Amtir 1) glass.
The application of this technique to chalcogenide glasses made at TI
and at AMI was the result of efforts by Don Hayes while at TI. Hayes
10
applied this method to characterize some of the TI sulfur and sele-
nium chalcogenide glasses shown in Table 4.7. Later, he published a
11
more complete treatment for Ge-Sb-S glasses. He was the one who
selected the equipment used by AMI.

4.3.3 Rupture Modulus
The rupture modulus is an experimentally determined value related
to the ability of the glass to resist fracture under the stress of force.

E (10 psi) G (10 psi) n
6
6
Se 1.43 0.545 0.315
Ge Sb Se 2.35 0.92 0.279
17.5 7.5 75
Ge Sb Se 2.56 1.00 0.278
21 9 70
Ge Sb Se (1173) 3.16 1.26 0.265
28 12 60
As Se 2.65 1.03 0.289
2 3
#20 3.17 1.26 0.266
#20 (Bell Labs ) 3.29 1.31 0.261
12
Ge S As 2.01 0.776 0.295
15 70 15
Ge S As 3.05 1.22 0.250
36 60 4
Ge S As 3.37 1.38 0.244
37 60 3
Ge S As 4.26 1.70 0.251
40 50 10
Ge S As 6.08 2.39 0.271
35 25 40
Ge Se S As 2.72 1.02 0.274
30 30 30 10
Ge Se Te As 3.00 1.18 0.270
20 25 30 25
TABLE 4.7 Elastic Moduli of Sulfur- and Selenium-Based Glasses