Glass compositions having high thermal and chemical stability and methods of making thereof
Described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs). In accordance with certain of its aspects, the glasses possess good dimensional stability as a function of temperature.
1. An alkali metal-free glass comprising in mole percent on an oxide basis:
SiO 2
64.0-72.0
Al 2 O 3
9.0-16.0
B 2 O 3
1.0-5.0
MgO + La 2 O 3
1.0-7.5
CaO
2.0-7.5
SrO
0.0-4.5
BaO
1.0-7.0
wherein:
(i) Σ(MgO+CaO+SrO+BaO+3La 2 O 3 )/(Al 2 O 3 )≧1.15, and
(ii) [MgO]:[CaO]:[SrO+BaO]=1±0.15: 1±0.15: 1±0.15,
where Al 2 O 3 , MgO, CaO, SrO, BaO, and La 2 O 3 represent the mole percents of the respective oxide components.
2. The alkali metal-free glass of claim 1 , wherein:
SiO 2
65.0-72.0
Al 2 O 3
10.0-15.0
B 2 O 3
1.0-4.0
MgO
2.0-7.5
CaO
3.0-6.0
SrO
0.0-4.5
BaO
1.0-6.0
La 2 O 3
0.0.
3. The glass of claim 1 , wherein: 1.20 ≦Σ(MgO+CaO+SrO+BaO+3La 2 O 3 )/(Al 2 O 3 ) 1.45.
4. The glass of claim 1 , wherein the glass has a strain point which satisfies the relationship:
700° C. ≦strain point ≦730° C.
5. The glass of claim 1 , wherein the glass exhibits a dimensional change of less than 30 ppm for a 5 minute heat treatment at 600° C.
6. The glass of claim 1 , wherein:
(a) SiO 2 is 66.5-70.5 mole percent; and/or
(b) B 2 O 3 is 1.0-4.0 mole percent; and/or
(c) MgO is 2.0-6.0 mole percent; and/or
(d) CaO is 2.0-6.5 mole percent.
7. The alkali metal-free glass of claim 1 , wherein:
(a) Σ(MgO+CaO+SrO+BaO+3La 2 O 3 )/(Al 2 O 3 )≦1.55;
(b) the glass has a strain point greater than or equal to 700° C.;
(c) the glass has a temperature at 200 poise viscosity less than or equal to 1,665° C.; and
(d) the glass has a viscosity at the liquidus temperature greater than or equal to 85,000 poise.
8. The glass of claim 1 , wherein the glass has one or more of the following properties:
(a) Σ(MgO+CaO+SrO+BaO+3La 2 O 3 )/(Al 2 O 3 )≧1.25; and/or
(b) Σ(MgO+CaO+SrO+BaO+3La 2 O 3 )/(Al 2 O 3 )≦1.55; and/or
(c) 1.25≦Σ(MgO+CaO+SrO+BaO+3La 2 O 3 )/(Al 2 O 3 )≦1.45.
9. The glass of claim 1 , wherein the glass has one or more of the following properties:
(a) a liquidus viscosity greater than or equal to 100,000 poise; and/or
(b) a linear coefficient of thermal expansion (CTE) of 28×10 −7 /° C. CTE ≦40×10 −7 /° C. over the temperature range of 0 to 300° C.; and/or
(c) a strain point greater than or equal to 710° C.; and/or
(d) a Young's modulus/density ratio greater than 30.0 GPa·cm 3 /g; and/or
(e) the glass is substantially free of As 2 O 3 ; and/or
(f) the glass is substantially free of As 2 O 3 and Sb 2 O 3 .
10. An alkali metal-free glass comprising in mole percent on an oxide basis:
SiO 2
65.0-71.0
Al 2 O 3
9.0-16.0
B 2 O 3
1.5-4.0
MgO + La 2 O 3
0.5-7.5
CaO
2.0-6.0
SrO
0.0-4.5
BaO
1.0-7.0
La 2 O 3
>0.0 and less than or equal to 4.0
wherein Σ(MgO+CaO+SrO+Ba 0 +3La 2 O 3 )/(Al 2 O 3 )≧1.2, where Al 2 O 3 , MgO, CaO, SrO, BaO, and La 2 O 3 represent the mole percents of the respective oxide components.
11. An alkali metal-free glass comprising SiO 2 , Al 2 O 3 , B 2 O 3 , MgO, CaO, optionally La 2 O 3 , and at least one of SrO and BaO, wherein the glass' composition satisfies the relationships:
(i) Σ(MgO+CaO+Sr 0 +Ba 0 +3La 2 O 3 )≧1.15, and
(ii) [MgO]:[CaO]:[SrO+BaO]=1±0.15 : 1±0.15 : 1±0.15, where Al 2 O 3 , MgO, CaO, SrO, BaO, and La 2 O 3 represent the mole percents of the respective oxide components.
12. The alkali metal-free glass of claim 11 , wherein the glass' composition satisfies the relationship:
[MgO]:[CaO]:[SrO+BaO]=1±0.1 : 1±0.1 : 1±0.1.
13. The alkali metal-free glass of claim 11 , wherein B 2 O 3 is less than or equal to 4.0 mole percent.
14. The alkali metal-free glass of claim 11 , wherein the BaO/SrO ratio in mole percent is equal to or greater than 2.0.
15. A liquid crystal display substrate comprising the glass of claim 1 .
16. A liquid crystal display substrate comprising the glass of claim 2 .
17. A liquid crystal display substrate comprising the glass of claim 10 .
18. A liquid crystal display substrate comprising the glass of claim 11 .