Alkali-free glass
An alkali-free glass having a strain point of 650° C. or more, an average coefficient of thermal expansion at 50 to 350° C. of from 30×10 −7 to 45×10 −7 /° C., and a temperature T 2 at which a glass viscosity reaches 10 2 dPa·s of from 1,500 to 1,800° C. The alkali-free glass contains, as represented by mol % based on oxides, SiO 2 : from 62 to 70%, Al 2 O 3 : from 9 to 16% B 2 O 3 : from 0 to 12%, MgO: from 3 to 10%, CaO: from 4 to 12%, SrO: from 0 to 6%, and Fe 2 O 3 : from 0.001 to 0.04%, provided that MgO+CaO+SrO+BaO is from 12 to 25%. The alkali-free glass has a β-OH value of from 0.35 to 0.85/mm.
1 . An alkali-free glass having a strain point of 650° C. or more, an average coefficient of thermal expansion at 50 to 350° C. of from 30×10 −7 to 45×10 −7 /° C., and a temperature T 2 at which a glass viscosity reaches 10 2 dPa·s of from 1,500 to 1,800° C., comprising, as represented by mol % based on oxides,
SiO 2 : from 62 to 70%,
Al 2 O 3 : from 9 to 16%
B 2 O 3 : from 0.5 to 12%,
MgO: from 5.6 to 10%,
CaO: from 4 to 10%,
SrO: from 0.1 to 6%, and
Fe 2 O 3 : from 0.001 to 0.04%,
provided that MgO+CaO+SrO+BaO is from 15.6 to 20.5%,
wherein a value represented by the following formula A is from 10 to 20:
(
3.119
×
10
-
4
T
2
2
-
0.2014
T
2
-
17.38
)
[
Fe
2
O
3
]
+
(
6.434
×
10
-
7
T
2
2
+
0.0144
T
2
-
7.842
)
[
β
-
OH
]
,
Formula
A
wherein [Fe 2 O 3 ] is a numerical value represented by mol % of a total iron in terms of Fe 2 O 3 , and
[β-OH] is a numerical value represented by a unit/mm.
2 . The alkali-free glass according to claim 1 , having a β-OH value of from 0.35 to 0.85/mm.
3 . The alkali-free glass according to claim 1 , having an effective thermal conductivity at the temperature T 2 at which the glass viscosity reaches 10 2 dPa·s of from 40 to 65 W/m·K.
4 . The alkali-free glass according to claim 1 , having a transmittance at a wavelength of 300 nm in terms of a plate thickness of 0.5 mm of 50% or more.
5 . The alkali-free glass according to claim 1 , having a glass plate shape and a thickness of from 0.05 mm to 3 mm.
6 . A method for producing the alkali-free glass according to claim 1 , comprising:
forming a molten glass by a float process or a fusion process.
7 . A display panel, comprising:
the alkali-free glass according to claim 1 .
8 . A semiconductor device, comprising:
the alkali-free glass according to claim 1 .
9 . An information recording medium, comprising:
the alkali-free glass according to claim 1 .