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Glasses are disclosed which are used to produce substrates in flat panel display devices. The glasses exhibit a density less than about 2.45 gm/cm 3 and a liquidus viscosity greater than about 200,000 poises, the glass consisting essentially of the following composition, expressed in terms of mol p

Glasses are disclosed which are used to produce substrates in flat panel display devices. The glasses exhibit a density less than about 2.45 gm/cm 3 and a liquidus viscosity greater than about 200,000 poises, the glass consisting essentially of the following composition, expressed in terms of mol percent on an oxide basis: 65-75 SiO 2 , 7-13 Al 2 O 3 , 5-15 B 2 O 3 , 0-3 MgO, 5-15 CaO, 0-5 SrO, and essentially free of BaO. The glasses also exhibit a strain point exceeding 650° C.

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1. An aluminosilicate glass exhibiting a density less than about 2.45 g/cm 3 and a liquidus viscosity greater than about 200,000 poises, the glass consisting essentially of the following composition as calculated in mol percent on an oxide basis: 65-75 SiO 2 , 7-13 Al 2 O 3 , 5-15 B 2 O 3 , 0-

1. An aluminosilicate glass exhibiting a density less than about 2.45 g/cm 3 and a liquidus viscosity greater than about 200,000 poises, the glass consisting essentially of the following composition as calculated in mol percent on an oxide basis: 65-75 SiO 2 , 7-13 Al 2 O 3 , 5-15 B 2 O 3 , 0-3 MgO, 5-15 CaO, 0-5 SrO, and less than about 0.1 BaO, wherein the glass has a linear coefficient of thermal expansion (CTE) over the temperature range 0-300° C. between 28-33×10 −7 /° C. 2. The glass of claim 1, wherein the RO/Al 2 O 3 ratio is between 0.9 and 1.2, wherein R represents Mg, Ca, Sr and Ba. 3. The glass of claim 1, wherein the glass has a strain point greater than about 650° C. 4. The glass of claim 1, wherein the glass has a strain point greater than about 660° C. 5. The glass of claim 1, wherein the glass has a melting temperature less than about 1700° C. 6. The glass of claim 1, wherein the glass exhibits a weight loss of less than 0.5 mg/cm 2 after immersion in a solution of 1 part 50 wt. % HF and 10 parts 40 wt. % NH 4 F for 5 minutes at 30° C. 7. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 400,000 poises. 8. A glass according to claim 1, wherein the glass has a liquidus viscosity greater than about 600,000 poises. 9. A glass according to claim 1, wherein the glass contains between 0-1 mole percent MgO when the glass contains no SrO. 10. In a flat panel display device, the improvement comprising a substrate in accordance with claim 1. 11. The flat panel display device of claim 10, wherein the substrate has an average surface roughness less than about 0.5 nm. 12. The flat panel display device of claim 10, wherein the substrate has an average internal stress less than about 150 psi. 13. A glass according to claim 1, wherein the glass has a composition consisting essentially of, as expressed in mol percent on an oxide basis: 67-73 SiO 2 , 8-11.5 Al 2 O 3 , 8-12 B 2 O 3 , 0-1 MgO, 5.5-11 CaO, and 0-5 SrO. 14. The glass of claim 13, wherein the glass has a strain point greater than about 650° C. 15. The glass of claim 13, wherein the glass has a strain point greater than about 660° C. 16. The glass of claim 13, wherein the glass has a melting temperature less than about 1700° C. 17. The glass of claim 13, wherein the glass has a liquidus viscosity greater than 400,000 poises. 18. The glass of claim 13, wherein the glass has a liquidus viscosity greater than about 800,000 poises. 19. In a flat panel display device, the improvement comprising a substrate in accordance with claim 13. 20. The flat panel display device of claim 19, wherein the substrate has an average surface roughness less than about 0.5 nm. 21. The flat panel display device of claim 19, wherein the substrate has an average internal stress less than about 150 psi. 22. In a flat panel display device, the improvement comprising a substrate in accordance with claim 18. 23. An aluminosilicate glass comprising in mol percent on an oxide basis: 65-75 SiO 2 , 7-13 Al 2 O 3 , and 5-15 B 2 O 3 , wherein:(a) said glass has a RO/Al 2 O 3 ratio between 0.9 and 1.2, wherein R represents Mg, Ca, Sr, and Ba;(b) the glass has a CaO concentration between 5 mol percent and 15 mol percent on an oxide basis; and(c) the glass has a density less than about 2.45 gram/cm 3 , a liquidus viscosity greater than about 200,000 poises, and a linear coefficient of thermal expansion over the temperature range from 0° C. to 300° C. between 28×10 −7 /° C. and 33×10 −7 /° C. 24. The glass of claim 23 wherein the glass comprises in mol percent on an oxide basis: 67-73 SiO 2 , 8-11.5 Al 2 O 3 , 8-12 B 2 O 3 , and 5.5-11 CaO. 25. The glass of claim 23, wherein the RO/Al 2 O 3 ratio is between 0.92 and 0.96, wherein R represents Mg, Ca, Sr, and Ba. 26. The glass of claim 23, wherein the glass has a strain point greater than abo ut 650° C. 27. The glass of claim 23, wherein the glass has a strain point greater than about 660° C. 28. The glass of claim 23, wherein the glass has a melting temperature less than about 1700° C. 29. The glass of claim 23, wherein the glass exhibits a weight loss of less than 0.5 mg/cm 2 after immersion in a solution of 1 part 50 wt. % HF and 10 parts 40 wt. % NH 4 F for 5 minutes at 30° C. 30. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 400,000 poises. 31. A glass according to claim 23, wherein the glass has a liquidus viscosity greater than about 600,000 poises. 32. A glass according to claim 23, wherein the glass has a liquidus viscosity greater than about 800,000 poises. 33. A glass according to claim 23, wherein the glass has a density less than about 2.40 gram/cm 3 . 34. In a flat panel display device, the improvement comprising a substrate comprising the glass of claim 23. 35. The flat panel display device of claim 34, wherein the substrate has an average surface roughness less than about 0.5 nm. 36. The flat panel display device of claim 34, wherein the substrate has an average internal stress less than about 150 psi. 37. The glass of claim 23, wherein the glass comprises less than about 0.1 mol percent BaO. 38. The glass of claim 23, wherein the glass comprises less than about 0.1 mol percent of alkali metal oxides. 39. The glass of claim 1 wherein the alkali metal oxide content of the glass is less than about 0.1 mol percent. 40. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 800,000 poises. 41. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 400,000 poises and a density less than about 2.40 gram/cm 3 . 42. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 600,000 poises and a density less than about 2.40 gram/cm 3 . 43. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 800,000 poises and a density less than about 2.40 gram/cm 3 . 44. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 400,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 650° C. 45. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 600,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 650° C. 46. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 800,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 650° C. 47. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 400,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 660° C. 48. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 600,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 660° C. 49. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 800,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 660° C. 50. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 400,000 poises, a density less than about 2.40 gram/cm 3 , and exhibits a weight loss of less than 0.5 mg/cm 2 after immersion in a solution of 1 part 50 wt. % HF and 10 parts 40 wt. % NH 4 F for 5 minutes at 30° C. 51. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 600,000 poises, a density less than about 2.40 gram/cm 3 , and exhibits a weight loss of less than 0.5 mg/cm 2 after immersion in a solution of 1 part 50 wt. % HF and 10 parts 40 wt. % NH 4 F for 5 minutes at 30° C. 52. The glass of claim 1, wherein the glass has a liquidus viscosity greater than about 800,000 poi ses, a density less than about 2.40 gram/cm 3 , and exhibits a weight loss of less than 0.5 mg/cm 2 after immersion in a solution of 1 part 50 wt. % HF and 10 parts 40 wt. % NH 4 F for 5 minutes at 30° C. 53. The flat panel display device of claim 10, wherein the substrate has an average surface roughness less than about 0.5 nm without polishing. 54. The flat panel displays device of claim 10, wherein the substrate has an average surface roughness less than about 0.5 nm and an average internal stress less than about 150 psi. 55. In a flat panel display device, the improvement comprising a substrate comprising the glass of claim 41 wherein the substrate has an average surface roughness less than about 0.5 nm. 56. In a flat panel display device, the improvement comprising a substrate comprising the glass of claim 42 wherein the substrate has an average surface roughness less than about 0.5 nm. 57. In a flat panel display device, the improvement comprising a substrate comprising the glass of claim 43 wherein the substrate has an average surface roughness less than about 0.5 nm. 58. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 400,000 poises and a density less than about 2.40 gram/cm 3 . 59. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 600,000 poises and a density less than about 2.40 gram/cm 3 . 60. The glass of claim 23, wherein the glass has a liquidus viscosity/greater than about 800,000 poises and a density less than about 2.40 gram/cm 3 . 61. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 400,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 650° C. 62. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 600,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 850° C. 63. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 800,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 650° C. 64. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 400,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 660° C. 65. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 600,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 660° C. 66. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 800,000 poises, a density less than about 2.40 gram/cm 3 , and a strain point greater than about 660° C. 67. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 400,000 poises, a density less than about 2.40 gram/cm 3 , and exhibits a weight loss of less than 0.5 mg/cm 2 after immersion in a solution of 1 part 50 wt. % HF and 10 parts 40 wt. % NH 4 F for 5 minutes at 30° C. 68. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 600,000 poises, a density less than about 2.40 gram/cm 3 , and exhibits a weight loss of less than 0.5 mg/cm 2 after immersion in a solution of 1 part 50 wt. % HF and 10 parts 40 wt. % NH 4 F for 5 minutes at 30° C. 69. The glass of claim 23, wherein the glass has a liquidus viscosity greater than about 800,000 poises, a density less than about 2.40 gram/cm 3 , and exhibits a weight loss of less than 0.5 mg/cm 2 after immersion in a solution oil 1 part 50 wt. % HF and 10 parts 40 wt. % NH 4 F for 5 minutes at 30° C. 70. The flat panel display device of claim 34, wherein the substrate has an average surface roughness less than about 0.5 nm without polishing. 71. The flat panel display device of claim 34, wherein the substrate has an average surface roughness less than about 0.5 nm and an average internal stress less than about 150 psi. 72. In a flat panel display device, the improvement comprising a substrate comprising the glass of claim 58 wherein the substrate has an average surface roughness less than about 0.5 nm. 73. In a flat panel display device, the improvement comprising a substrate comprising the glass of claim 59 wherein the substrate has an average surface roughness less than about 0.5 nm. 74. In a flat panel display device, the improvement comprising a substrate comprising the glass of claim 60 wherein the substrate has an average surface roughness less than about 0.5 nm.