Dilametric studies on Ge-Sb-Se classes

Results of measurements of the thermal expansion coefficient from room temperature up to the softening temperature on several compositions of the Ge-Sb-Se glass system are reported. The a -T data for these glasses have two region A below Tg where a is essentially constant followed by a region B around Tg where a increases with temperature. In the region A the composition dependence is identical for the three families of glasses studied, with the a-composition data showing an angularity at the corresponding stoichiometric composition of each family, while changes in a of about eighty percent are seen for compositions across a family, the change in a over the stoichiometric compositions is about fifteen per cent .An expression of the form a=za,x, where a, and x, are the expansion coefficients and weight fractions respectively of the individual structural units is found to account satisfactorily for the a-composition data of these glasses.In the region B,A increases with temperature .The increase in a is greater and begins at about 30to40 degrees lower than Tg for the SE-RICH GLASSES AS COMPARED TO THE Ge-rich glasses,where the increase is less and begins at T