Page 54 - Chalcogenide Glasses for Infrared Optics

32 Cha pte r T w o

Weight

Inert gas

Quartz rod

Heater

Sample

Sample holder

FIGURE 2.6 Simple apparatus for measuring glass softening point.

For a three-component ternary system, many samples are required.
Table 2.1 lists over 50 samples prepared in the evaluation of the
14
Si-P-Te system, a system evaluated early in the exploratory program
at TI. The 39 samples evaluated, identified by number, are plotted in
their respective composition points in the compositional triangular
diagram shown in Fig. 2.7. The glass forming composition region is
designated to lie within the dashed lines. Again, note that the extent
of this region is dependent on the quenching procedure as well as
the composition. For example, quenching in a cool liquid would
enlarge the area. The evaluation results indicated a system that was
not promising.
The glass forming region is smaller than that of the first system
13
evaluated at TI, the Si-As-Te system. Comparison of the sizes of
glass forming regions indicates differences in the glass forming ten-
dencies of different element combinations. The conclusions reached