Ternary glass materials with low refractive index variability
Ternary chalcogenide glass materials containing germanium can display enhanced properties compared to corresponding binary chalcogenide glass materials lacking germanium. For instance, ternary chalcogenide glass materials containing germanium, arsenic and selenium can exhibit improved Vickers micro-hardness values and other enhanced mechanical properties while still maintaining small changes in refractive index as function of temperature. Such ternary glass materials can have a formula of (As y Se z ) [(100-x)·0.01] Ge x , in which x ranges between about 1 and 5, y ranges between about 30 and 40, z ranges between about 60 and 70, and y+z=100. Methods for producing the ternary glass materials can include blending arsenic, selenium, and germanium as a melt, and cooling the melt to form the ternary glass material.
1. A composition comprising a ternary glass material, the ternary glass material having a formula of
(As y Se z ) [(100-x)·0.01 ]Ge x ;
wherein x ranges between about 1 and 5, y ranges between about 30 and 40, z ranges between about 60 and 70, and y+z=100.
2. The composition of claim 1 , wherein the ternary glass material has an index of refraction that varies by less than about 20 ppm/° C.
3. The composition of claim 2 , wherein the ternary glass material is heated and cooled multiple times below the glass transition temperature until the index of refraction remains substantially unchanged at a given temperature.
4. The composition of claim 1 , wherein the ternary glass material has a transmission window of at least about 1 micron to about 12 microns.
5. The composition of claim 1 , wherein the ternary glass material has a Vickers micro-hardness of about 1.5 GPa or greater at a 100 mN load.
6. The composition of claim 1 , wherein y ranges between about 30 and 35 and z ranges between about 65 and 70.
7. The composition of claim 1 , wherein y ranges between about 35 and 40 and z ranges between about 60 and 65.
8. The composition of claim 1 , wherein x ranges between about 1 and 3, y ranges between about 32.5 and 35, and z ranges between about 65 and 67.5.
9. The composition of claim 1 , wherein x ranges between about 3 and 5, y ranges between about 30 and 32.5, and z ranges between about 67.5 and 70.
10. The composition of claim 1 , wherein x ranges between about 4 and 5, y ranges between about 30 and 31, and z ranges between about 69 and 70.
11. The composition of claim 1 , wherein the ternary glass material consists essentially of about 29.7-39.6 atomic percent arsenic, about 59.4-69.3 atomic percent selenium, and about 1-5 atomic percent germanium.
12. An optical structure comprising the composition of claim 1 .
13. A method comprising:
blending a mixture comprising about 29.7-39.6 atomic percent arsenic, about 59.4-69.3 atomic percent selenium, and about 1-5 atomic percent germanium as a melt; and
cooling the melt to form a ternary glass material.
14. The method of claim 13 , further comprising:
performing a first annealing cycle in which the ternary glass material is heated to a temperature below the glass transition temperature and then cooled; and
performing one or more subsequent annealing cycles until the refractive index of the ternary glass material remains substantially unchanged at a given temperature from that of a prior annealing cycle.
15. The method of claim 13 , wherein the ternary glass material has a formula of
(As y Se z ) [(100-x)·0.01] Ge x ;
wherein x ranges between about 1 and 5, y ranges between about 30 and 40, z ranges between about 60 and 70, and y+z=100.
16. The method of claim 15 , wherein y ranges between about 30 and 35 and z ranges between about 65 and 70.
17. The method of claim 15 , wherein y ranges between about 35 and 40 and z ranges between about 60 and 65.
18. The method of claim 15 , wherein x ranges between about 1 and 3, y ranges between about 32.5 and 35, and z ranges between about 65 and 67.5.
19. The method of claim 15 , wherein x ranges between about 3 and 5, y ranges between about 30 and 32.5, and z ranges between about 67.5 and 70.
20. The method of claim 15 , wherein x ranges between about 4 and 5, y ranges between about 30 and 31, and z ranges between about 69 and 70.
21. The method of claim 13 , wherein the ternary glass material consists essentially of arsenic, selenium, and germanium.