U.S. patent application number 16/217900 was filed with the patent office on 2019-04-18 for fusion formable sodium free glass.
This patent application is currently assigned to Corsam Technologies LLC. The applicant listed for this patent is Corsam Technologies LLC. Invention is credited to Bruce Gardiner AITKEN, James Edward DICKINSON, JR., Timothy J. KICZENSKI, Michelle Diane PIERSON-STULL.
Application Number | 20190112219 16/217900 |
Document ID | / |
Family ID | 43218848 |
Filed Date | 2019-04-18 |
United States Patent
Application |
20190112219 |
Kind Code |
A1 |
AITKEN; Bruce Gardiner ; et
al. |
April 18, 2019 |
Fusion Formable Sodium Free Glass
Abstract
A compositional range of fusion-formable, high strain point
sodium free, silicate, aluminosilicate and boroaluminosilicate
glasses are described herein. The glasses can be used as substrates
for photovoltaic devices, for example, thin film photovoltaic
devices such as CIGS photovoltaic devices. These glasses can be
characterized as having strain points.gtoreq.540.degree. C.,
thermal expansion coefficient of from 6.5 to 10.5 ppm/.degree. C.,
as well as liquidus viscosities in excess of 50,000 poise. As such
they are ideally suited for being formed into sheet by the fusion
process.
Inventors: |
AITKEN; Bruce Gardiner;
(Corning, NY) ; DICKINSON, JR.; James Edward;
(Corning, NY) ; KICZENSKI; Timothy J.; (Corning,
NY) ; PIERSON-STULL; Michelle Diane; (Painted Post,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Corsam Technologies LLC |
Corning |
NY |
US |
|
|
Assignee: |
Corsam Technologies LLC
Corning
NY
|
Family ID: |
43218848 |
Appl. No.: |
16/217900 |
Filed: |
December 12, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15651654 |
Jul 17, 2017 |
10173919 |
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16217900 |
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15041697 |
Feb 11, 2016 |
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15651654 |
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12788763 |
May 27, 2010 |
9371247 |
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15041697 |
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61182404 |
May 29, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02P 70/521 20151101;
C03C 3/091 20130101; C03C 3/064 20130101; H01L 31/0296 20130101;
Y02E 10/541 20130101; Y02P 70/50 20151101; H01L 31/048 20130101;
C03C 3/089 20130101; H01L 31/0322 20130101; C03C 3/078
20130101 |
International
Class: |
C03C 3/064 20060101
C03C003/064; H01L 31/0296 20060101 H01L031/0296; C03C 3/089
20060101 C03C003/089; H01L 31/048 20060101 H01L031/048; C03C 3/078
20060101 C03C003/078; H01L 31/032 20060101 H01L031/032; C03C 3/091
20060101 C03C003/091 |
Claims
1. A glass comprising, in weight percent: 35 to 75 percent
SiO.sub.2; 0 to 15 percent Al.sub.2O.sub.3; 0 to 20 percent
B.sub.2O.sub.3; 3 to 30 percent K.sub.2O; 0 to 15 percent MgO; 0 to
10 percent CaO; 0 to 12 percent SrO; 0 to 40 percent BaO; and 0 to
1 percent SnO.sub.2, wherein the glass is substantially free of
Na.sub.2O.
2. The glass according to claim 1, comprising: greater than 0
percent B.sub.2O.sub.3.
3. The glass according to claim 1, wherein the glass is
substantially free of B.sub.2O.sub.3.
4. The glass according to claim 1, comprising: at least 45 percent
SiO.sub.2.
5. The glass according to claim 1, comprising: greater than 0
percent MgO, CaO, SrO, or combinations thereof.
6. The glass according to claim 1 comprising, in weight percent: 35
to 75 percent SiO.sub.2; greater than 0 to 15 percent
Al.sub.2O.sub.3; greater than 0 to 20 percent B.sub.2O.sub.3; 3 to
30 percent K.sub.2O; greater than 0 to 15 percent MgO; greater than
0 to 10 percent CaO; greater than 0 to 12 percent SrO; greater than
0 to 40 percent BaO; and greater than 0 to 1 percent SnO.sub.2,
wherein the glass is substantially free of Na.sub.2O.
7. The glass according to claim 1, comprising: 39 to 75 percent
SiO.sub.2; 2 to 13 percent Al.sub.2O.sub.3; 1 to 11 percent
B.sub.2O.sub.3; 3 to 30 percent K.sub.2O; 0 to 7 percent MgO; 0 to
10 percent CaO; 0 to 12 percent SrO; 0 to 40 percent BaO; and 0 to
1 percent SnO.sub.2, wherein the glass is substantially free of
Na.sub.2O.
8. The glass according to claim 1, comprising: 50 to 70 percent
SiO.sub.2; 2 to 13 percent Al.sub.2O.sub.3; 1 to 11 percent
B.sub.2O.sub.3; 3 to 30 percent K.sub.2O; 0 to 7 percent MgO; 0 to
7 percent CaO; 0 to 5 percent SrO; 1 to 40 percent BaO; and 0 to
0.3 percent SnO.sub.2, wherein the glass is substantially free of
Na.sub.2O.
9. The glass according to claim 1, wherein the glass is in the form
of a sheet.
10. The glass according to claim 9, wherein the sheet has a
thickness in the range of from 0.5 mm to 3.0 mm.
11. A photovoltaic device comprising the glass according to claim
1.
12. The photovoltaic device according to claim 11, comprising a
functional layer comprising copper indium gallium diselenide or
cadmium telluride adjacent to the substrate or superstrate.
13. The photovoltaic device according to claim 12, further
comprising a barrier layer disposed between the superstrate or
substrate and the functional layer.
14. The glass according to claim 1, having a strain point of
540.degree. C. or greater.
15. The glass according to claim 1, having a coefficient of thermal
expansion of 50.times.10.sup.-7 or greater.
16. The glass according to claim 1, having a coefficient of thermal
expansion in the range of from 50.times.10.sup.-7 to
90.times.10.sup.-7.
17. The glass according to claim 1, having a strain point of
560.degree. C. or greater and a coefficient of thermal expansion of
50.times.10.sup.-7 or greater.
18. The glass according to claim 1, having a liquidus viscosity of
50,000 poise or greater.
19. The glass according to claim 1, having a T.sub.200 less than
1580.degree. C. and a liquidus viscosity of 400,000 poise or
greater.
20. The glass according to claim 1, wherein the glass is fusion
formable and has a strain point of 540.degree. C. or greater, a
coefficient of thermal expansion of 50.times.10.sup.-7 or greater,
T.sub.200 less than 1630.degree. C., and having a liquidus
viscosity of 150,000 poise or greater.
21. A glass consisting essentially of, in weight percent: 35 to 75
percent SiO.sub.2; 0 to 15 percent Al.sub.2O.sub.3; 0 to 20 percent
B.sub.2O.sub.3; 3 to 30 percent K.sub.2O; 0 to 15 percent MgO; 0 to
10 percent CaO; 0 to 12 percent SrO; 0 to 40 percent BaO; and 0 to
1 percent SnO.sub.2, wherein the glass is substantially free of
Na.sub.2O.
22. A glass comprising, in weight percent: 45 to 75 percent
SiO.sub.2; 3 to 15 percent Al.sub.2O.sub.3; 0 to 20 percent
B.sub.2O.sub.3; 14 to 25 percent K.sub.2O; 0 to 15 percent MgO; 0
to 10 percent CaO; 0 to 12 percent SrO; 0 to 40 percent BaO; and 0
to 1 percent SnO.sub.2, wherein the glass is substantially free of
Na.sub.2O and wherein the glass is fusion formable and has a strain
point of 540.degree. C. or greater, a coefficient of thermal
expansion of 50.times.10.sup.-7 or greater, T.sub.200 less than
1630.degree. C., and having a liquidus viscosity of 150,000 poise
or greater.
23. A glass comprising, in weight percent: 45 to 75 percent
SiO.sub.2; 3 to 15 percent Al.sub.2O.sub.3; 0 to 20 percent
B.sub.2O.sub.3; 3 to 30 percent K.sub.2O; 0 to 15 percent MgO; 0 to
10 percent CaO; 0 to 12 percent SrO; 0 to 40 percent BaO; and 0 to
1 percent SnO.sub.2, wherein the glass is substantially free of
Na.sub.2O and wherein the glass is fusion formable and has a strain
point of 540.degree. C. or greater, a coefficient of thermal
expansion of 50.times.10.sup.-7 or greater, T.sub.200 less than
1630.degree. C., and having a liquidus viscosity of 150,000 poise
or greater.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 15/651,654 filed on Jul. 17, 2017, which is a continuation of
U.S. application Ser. No. 15/041,697 filed Feb. 11, 2016, now
abandoned, which is a continuation of U.S. application Ser. No.
12/788,763 filed on May 27, 2010, now U.S. Pat. No. 9,371,247,
which claims the benefit of priority to U.S. Provisional
Application No. 61/182404 filed on May 29, 2009.
BACKGROUND
Field
[0002] Embodiments relate generally to sodium free glasses and more
particularly to fusion formable sodium free glasses which may be
useful in photochromic, electrochromic, Organic Light Emitting
Diode (OLED) lighting, or photovoltaic applications, for example,
thin film photovoltaics.
Technical Background
[0003] The fusion forming process typically produces flat glass
with optimal surface and geometric characteristics useful for many
electronics applications, for instance, substrates used in
electronics applications, for example, display glass for LCD
televisions.
[0004] Over the last 10 years, Corning fusion glass products
include 1737F.TM., 1737G.TM., Eagle2000F.TM., EagleXG.TM.,
Jade.TM., and Codes 1317 and 2317 (Gorilla Glass.TM.). Efficient
melting is generally believed to occur at a temperature
corresponding to a melt viscosity of about 200 poise (p). These
glasses share in common 200p temperatures in excess of 1600.degree.
C., which can translate to accelerated tank and electrode
corrosion, greater challenges for fining due to still more elevated
finer temperatures, and/or reduced platinum system life time,
particularly around the finer. Many have temperatures at 3000 poise
in excess of about 1300.degree. C., and since this is a typical
viscosity for an optical stirrer, the high temperatures at this
viscosity can translate to excessive stirrer wear and elevated
levels of platinum defects in the body of the glass.
[0005] Many of the above described glasses have delivery
temperatures in excess of 1200.degree. C., and this can contribute
to creep of isopipe refractory materials, particularly for large
sheet sizes.
[0006] These attributes combine so as to limit flow (because of
slow melt rates), to accelerate asset deterioration, to force
rebuilds on timescales much shorter than product lifetimes, to
force unacceptable (arsenic), expensive (capsule) or unwieldy
(vacuum fining) solutions to defect elimination, and thus
contribute in significant ways to the cost of manufacturing
glass.
[0007] In applications in which rather thick, comparatively
low-cost glass with less extreme properties is required, these
glasses are not only overkill, but prohibitively expensive to
manufacture. This is particularly true when the competitive
materials are made by the float process, a very good process for
producing low cost glass with rather conventional properties. In
applications that are cost sensitive, such as large-area
photovoltaic panels and OLED lighting, this cost differential is so
large as to make the price point of LCD-type glasses
unacceptable.
[0008] To reduce such costs, it is advantageous to drive down the
largest overall contributors (outside of finishing), and many of
these track directly with the temperatures used in the melting and
forming process. Therefore, there is a need for a glass that melts
at a lower temperature than those aforementioned glasses.
[0009] Further, it would be advantageous to have a glass useful for
low temperature applications, for instance, photovoltaic and OLED
light applications. Further, it would be advantageous to have a
glass whose processing temperatures were low enough that the
manufacturing of the glass would not excessively consume the energy
that these applications are aiming to save.
SUMMARY
[0010] A compositional range of fusion-formable, high strain point
sodium free, silicate, aluminosilicate and boroaluminosilicate
glasses useful, for example, for thin-film photovoltaic
applications are described herein. More specifically, these glasses
are advantageous materials to be used in copper indium gallium
diselenide (CIGS) photovoltaic modules where the sodium required to
optimize cell efficiency is not to be derived from the substrate
glass but instead from a separate deposited layer consisting of a
sodium containing material such as NaF. Current CIGS module
substrates are typically made from soda-lime glass sheet that has
been manufactured by the float process. However, use of higher
strain point glass substrates can enable higher temperature CIGS
processing, which is expected to translate into desirable
improvements in cell efficiency. Moreover, it may be that the
smoother surface of fusion-formed glass sheets yields additional
benefits, such as improved film adhesion, etc.
[0011] Accordingly, the sodium free glasses described herein can be
characterized by strain points 540.degree. C., for example,
560.degree. C. so as to provide advantage with respect to soda-lime
glass and/or liquidus viscosity 30,000 poise to allow manufacture
via the fusion process. In order to avoid thermal expansion
mismatch between the substrate and CIGS layer, the inventive
glasses are further characterized by a thermal expansion
coefficient in the range of from 6.5 to 10.5 ppm/.degree. C.
[0012] One embodiment is a glass comprising, in weight percent:
[0013] 35 to 75 percent SiO.sub.2; [0014] 0 to 15 percent
Al.sub.2O.sub.3; [0015] 0 to 20 percent B.sub.2O.sub.3; [0016] 3 to
30 percent K.sub.2O; [0017] 0 to 15 percent MgO; [0018] 0 to 10
percent CaO; [0019] 0 to 12 percent SrO; [0020] 0 to 40 percent
BaO; and [0021] 0 to 1 percent SnO.sub.2,
[0022] wherein the glass is substantially free of Na.sub.2O.
[0023] In another embodiment, the glass comprises, in weight
percent: [0024] 35 to 75 percent SiO.sub.2; [0025] greater than 0
to 15 percent Al.sub.2O.sub.3; [0026] greater than 0 to 20 percent
B.sub.2O.sub.3; [0027] 3 to 30 percent K.sub.2O; [0028] greater
than 0 to 15 percent MgO; [0029] greater than 0 to 10 percent CaO;
[0030] greater than 0 to 12 percent SrO; [0031] greater than 0 to
40 percent BaO; and [0032] greater than 0 to 1 percent
SnO.sub.2,
[0033] wherein the glass is substantially free of Na.sub.2O.
[0034] In another embodiment, the glass comprises, in weight
percent: [0035] 39 to 75 percent SiO.sub.2; [0036] 2 to 13 percent
Al.sub.2O.sub.3; [0037] 1 to 11 percent B.sub.2O.sub.3; [0038] 3 to
30 percent K.sub.2O; [0039] 0 to 7 percent MgO; [0040] 0 to 10
percent CaO; [0041] 0 to 12 percent SrO; [0042] 0 to 40 percent
BaO; and [0043] 0 to 1 percent SnO.sub.2,
[0044] wherein the glass is substantially free of Na.sub.2O.
[0045] In another embodiment, the glass comprises, in weight
percent: [0046] 50 to 70 percent SiO.sub.2; [0047] 2 to 13 percent
Al.sub.2O.sub.3; [0048] 1 to 11 percent B.sub.2O.sub.3; [0049] 3 to
30 percent K.sub.2O; [0050] 0 to 7 percent MgO; [0051] 0 to 7
percent CaO; [0052] 0 to 5 percent SrO; [0053] 1 to 40 percent BaO;
and [0054] 0 to 0.3 percent SnO.sub.2,
[0055] wherein the glass is substantially free of Na.sub.2O.
[0056] Another embodiment is a glass consisting essentially of, in
weight percent: [0057] 35 to 75 percent SiO.sub.2; [0058] 0 to 15
percent Al.sub.2O.sub.3; [0059] 0 to 20 percent B.sub.2O.sub.3;
[0060] 3 to 30 percent K.sub.2O; [0061] 0 to 15 percent MgO; [0062]
0 to 10 percent CaO; [0063] 0 to 12 percent SrO; [0064] 0 to 40
percent BaO; and [0065] 0 to 1 percent SnO.sub.2,
[0066] wherein the glass is substantially free of Na.sub.2O.
[0067] Another embodiment is a glass comprising, in weight percent:
[0068] 45 to 75 percent SiO.sub.2; [0069] 3 to 15 percent
Al.sub.2O.sub.3; [0070] 0 to 20 percent B.sub.2O.sub.3; [0071] 14
to 25 percent K.sub.2O; [0072] 0 to 15 percent MgO; [0073] 0 to 10
percent CaO; [0074] 0 to 12 percent SrO; [0075] 0 to 40 percent
BaO; and [0076] 0 to 1 percent SnO.sub.2,
[0077] wherein the glass is substantially free of Na.sub.2O and
wherein the glass is fusion formable and has a strain point of
540.degree. C. or greater, a coefficient of thermal expansion of
50.times.10.sup.-7 or greater, T.sub.200 less than 1630.degree. C.,
and having a liquidus viscosity of 150,000 poise or greater.
[0078] Additional features and advantages will be set forth in the
detailed description which follows, and in part will be readily
apparent to those skilled in the art from the description or
recognized by practicing the invention as described in the written
description and claims hereof.
[0079] It is to be understood that both the foregoing general
description and the following detailed description are merely
exemplary of the invention, and are intended to provide an overview
or framework for understanding the nature and character of the
invention as it is claimed.
DETAILED DESCRIPTION
[0080] Reference will now be made in detail to various embodiments
of the invention.
[0081] As used herein, the term "substrate" can be used to describe
either a substrate or a superstrate depending on the configuration
of the photovoltaic cell. For example, the substrate is a
superstrate, if when assembled into a photovoltaic cell, it is on
the light incident side of a photovoltaic cell. The superstrate can
provide protection for the photovoltaic materials from impact and
environmental degradation while allowing transmission of the
appropriate wavelengths of the solar spectrum. Further, multiple
photovoltaic cells can be arranged into a photovoltaic module.
Photovoltaic device can describe either a cell, a module, or
both.
[0082] As used herein, the term "adjacent" can be defined as being
in close proximity. Adjacent structures may or may not be in
physical contact with each other. Adjacent structures can have
other layers and/or structures disposed between them.
[0083] One embodiment is a glass comprising, in weight percent:
[0084] 35 to 75 percent SiO.sub.2; [0085] 0 to 15 percent
Al.sub.2O.sub.3; [0086] 0 to 20 percent B.sub.2O.sub.3; [0087] 3 to
30 percent K.sub.2O; [0088] 0 to 15 percent MgO; [0089] 0 to 10
percent CaO; [0090] 0 to 12 percent SrO; [0091] 0 to 40 percent
BaO; and [0092] 0 to 1 percent SnO.sub.2,
[0093] wherein the glass is substantially free of Na.sub.2O.
[0094] Another embodiment is a glass comprising, in weight percent:
[0095] 45 to 75 percent SiO.sub.2; [0096] 3 to 15 percent
Al.sub.2O.sub.3; [0097] 0 to 20 percent B.sub.2O.sub.3; [0098] 14
to 25 percent K.sub.2O; [0099] 0 to 15 percent MgO; [0100] 0 to 10
percent CaO; [0101] 0 to 12 percent SrO; [0102] 0 to 40 percent
BaO; and [0103] 0 to 1 percent SnO.sub.2,
[0104] wherein the glass is substantially free of Na.sub.2O and
wherein the glass is fusion formable and has a strain point of
540.degree. C. or greater, a coefficient of thermal expansion of
50.times.10.sup.-7 or greater, T.sub.200 less than 1630.degree. C.,
and having a liquidus viscosity of 150,000 poise or greater.
[0105] In another embodiment, the glass consists essentially of in
weight percent: [0106] 45 to 75 percent SiO.sub.2; [0107] 3 to 15
percent Al.sub.2O.sub.3; [0108] 0 to 20 percent B.sub.2O.sub.3;
[0109] 14 to 25 percent K.sub.2O; [0110] 0 to 15 percent MgO;
[0111] 0 to 10 percent CaO; [0112] 0 to 12 percent SrO; [0113] 0 to
40 percent BaO; and [0114] 0 to 1 percent SnO.sub.2,
[0115] wherein the glass is substantially free of Na.sub.2O and
wherein the glass is fusion formable and has a strain point of
540.degree. C. or greater, a coefficient of thermal expansion of
50.times.10.sup.-7 or greater, T.sub.200 less than 1630.degree. C.,
and having a liquidus viscosity of 150,000 poise or greater.
[0116] The glass is substantially free of Na.sub.2O, for example,
the content of Na.sub.2O can be 0.05 weight percent or less, for
example, zero weight percent. The glass, according to some
embodiments, is free of intentionally added sodium.
[0117] In some embodiments, the glass comprises greater than 3
percent K.sub.2O, for example, greater than 5 percent K.sub.2O, for
example, greater than 10 percent K.sub.2O, for example, greater
than 12 percent K.sub.2O, for example greater than 13.5 percent
K.sub.2O, for example, greater than 15 percent K.sub.2O.
[0118] Since the glass is substantially free of Na.sub.2O, in some
embodiments, the weight percent of the combination of Na.sub.2O and
K.sub.2O is greater than 3 percent, for example, greater than 5
percent, for example, greater than 10 percent, for example, greater
than 12 percent, for example greater than 13.5 percent, for
example, greater than 15 percent.
[0119] In some embodiments, the glass comprises at least 45 percent
SiO.sub.2, for example, at least 50 percent SiO.sub.2, for example,
at least 60 percent SiO.sub.2.
[0120] The glass, in one embodiment, is rollable. The glass, in one
embodiment, is down-drawable. The glass can be slot drawn or fusion
drawn, for example. According to another embodiment the glass can
be float formed.
[0121] The glass can further comprise 3 weight percent or less, for
example, 0 to 3 weight percent, for example, greater than 0 to 3
weight percent, for example, 1 to 3 weight percent of TiO.sub.2,
MnO, ZnO, Nb.sub.2O.sub.5, MoO.sub.3, Ta.sub.2O.sub.5, WO.sub.3,
ZrO.sub.2, Y.sub.2O.sub.3, La.sub.2O.sub.3, HfO.sub.2, CdO,
SnO.sub.2, Fe.sub.2O.sub.3, CeO.sub.2, As.sub.2O.sub.3,
Sb.sub.2O.sub.3, Cl, Br, or combinations thereof.
[0122] In some embodiments, the glass is substantially free of
ZrO.sub.2. In some embodiments, the glass is substantially free of
ZnO. The glass, in one embodiment, comprises 3 weight percent or
less, for example, 0 to 3 weight percent, for example, greater than
0 to 3 weight percent, for example, 1 to 3 weight percent of
TiO.sub.2.
[0123] As mentioned above, the glasses, according some embodiments,
comprise greater than 0 weight percent B.sub.2O.sub.3, for example,
1 weight percent or more, or, for example, 0 to 11 weight percent,
for example, greater than 0 to 11 weight percent B.sub.2O.sub.3,
for example, 0.5 to 11 weight percent B.sub.2O.sub.3, for example 1
to 11 weight percent B.sub.2O.sub.3. B.sub.2O.sub.3 is added to the
glass to reduce melting temperature, to decrease liquidus
temperature, to increase liquidus viscosity, and to improve
mechanical durability relative to a glass containing no
B.sub.2O.sub.3.
[0124] According to some embodiments, the glass is substantially
free of B.sub.2O.sub.3. In some embodiments, the glass is
substantially free of B.sub.2O.sub.3 and comprises at least 45
percent SiO.sub.2, for example, at least 50 percent SiO.sub.2, for
example, at least 60 percent SiO.sub.2.
[0125] The glass, according to some embodiments, comprises 30
weight percent total RO or less wherein RO is R is an alkaline
earth metal selected from Mg, Ca, Ba, and Sr, for example, 20
weight percent total RO or less, for example, 15 weight percent
total RO or less, for example, 13.5 weight percent total RO or
less.
[0126] The glass can comprise, for example, 0 to 15, greater than 0
to 15 weight percent, for example, 1 to 15 weight percent MgO. The
glass can comprise, for example, 0 to 7, greater than 0 to 7 weight
percent, for example, 1 to 7 weight percent MgO. MgO can be added
to the glass to reduce melting temperature and to increase strain
point. It can disadvantageously lower CTE relative to other
alkaline earths (e.g., CaO, SrO, BaO), and so other adjustments may
be made to keep the CTE within the desired range. Examples of
suitable adjustments include increase SrO at the expense of CaO,
increasing alkali oxide concentration, and replacing a smaller
alkali oxide in part with a larger alkali oxide.
[0127] According to another embodiment, the glass is substantially
free of BaO. For example, the content of BaO can be 0.05 weight
percent or less, for example, zero weight percent.
[0128] In some embodiments, the glass is substantially free of
Sb.sub.2O.sub.3, As.sub.2O.sub.3, or combinations thereof, for
example, the glass comprises 0.05 weight percent or less of
Sb.sub.2O.sub.3 or As.sub.2O.sub.3 or a combination thereof. For
example, the glass can comprise zero weight percent of
Sb.sub.2O.sub.3 or As.sub.2O.sub.3 or a combination thereof.
[0129] The glasses, in some embodiments, comprise 0 to 10 weight
percent CaO, for example, 0 to 7 weight percent CaO, or, for
example, greater than 0, for example, 1 to 10 weight percent CaO,
for example, 1 to 7 weight percent CaO. Relative to alkali oxides
or SrO, CaO contributes to higher strain point, lower density, and
lower melting temperature.
[0130] The glasses can comprise, in some embodiments, 0 to 12
weight percent SrO, for example, greater than zero to 12 weight
percent, for example, 1 to 12 weight percent SrO, or for example, 0
to 5 weight percent SrO, for example, greater than zero to 5 weight
percent, for example, 1 to 5 weight percent SrO. In certain
embodiments, the glass contains no deliberately batched SrO, though
it may of course be present as a contaminant in other batch
materials. SrO contributes to higher coefficient of thermal
expansion, and the relative proportion of SrO and CaO can be
manipulated to improve liquidus temperature, and thus liquidus
viscosity. SrO is not as effective as CaO or MgO for improving
strain point, and replacing either of these with SrO tends to cause
the melting temperature to increase.
[0131] Alkali cations such as K raise the CTE steeply, but also
lower the strain point and, depending upon how they are added,
increase melting temperatures. The least effective alkali oxide for
CTE is Li.sub.2O, and the most effective alkali oxide is
Cs.sub.2O.
[0132] Another embodiment is a glass consisting essentially of, in
weight percent: [0133] 35 to 75 percent SiO.sub.2; [0134] 0 to 15
percent Al.sub.2O.sub.3; [0135] 0 to 20 percent B.sub.2O.sub.3;
[0136] 3 to 30 percent K.sub.2O; [0137] 0 to 15 percent MgO; [0138]
0 to 10 percent CaO; [0139] 0 to 12 percent SrO; [0140] 0 to 40
percent BaO; and [0141] 0 to 1 percent SnO.sub.2,
[0142] wherein the glass is substantially free of Na.sub.2O.
[0143] The glass, according to some embodiments, is down-drawable;
that is, the glass is capable of being formed into sheets using
down-draw methods such as, but not limited to, fusion draw and slot
draw methods that are known to those skilled in the glass
fabrication arts. Such down-draw processes are used in the
large-scale manufacture of ion-exchangeable flat glass.
[0144] The fusion draw process uses a drawing tank that has a
channel for accepting molten glass raw material. The channel has
weirs that are open at the top along the length of the channel on
both sides of the channel. When the channel fills with molten
material, the molten glass overflows the weirs. Due to gravity, the
molten glass flows down the outside surfaces of the drawing tank.
These outside surfaces extend down and inwardly so that they join
at an edge below the drawing tank. The two flowing glass surfaces
join at this edge to fuse and form a single flowing sheet. The
fusion draw method offers the advantage that, since the two glass
films flowing over the channel fuse together, neither outside
surface of the resulting glass sheet comes in contact with any part
of the apparatus. Thus, the surface properties are not affected by
such contact.
[0145] The slot draw method is distinct from the fusion draw
method. Here the molten raw material glass is provided to a drawing
tank. The bottom of the drawing tank has an open slot with a nozzle
that extends the length of the slot. The molten glass flows through
the slot/nozzle and is drawn downward as a continuous sheet
therethrough and into an annealing region. Compared to the fusion
draw process, the slot draw process provides a thinner sheet, as
only a single sheet is drawn through the slot, rather than two
sheets being fused together, as in the fusion down-draw
process.
[0146] In order to be compatible with down-draw processes, the
glass described herein has a high liquidus viscosity. In one
embodiment, the glass has a liquidus viscosity of 50,000 poise or
greater, for example, 150,000 poise or greater, for example,
200,000 poise or greater, for example, 250,000 poise or greater,
for example, 300,000 poise or greater, for example, 350,000 poise
or greater, for example, 400,000 poise or greater, for example,
greater than or equal to 500,000 poise. The liquidus viscosities of
some exemplary glasses are closely correlated with the difference
between the liquidus temperature and the softening point. For
downdraw processes, some exemplary glasses advantageously have
liquidus--softening point less than about 230.degree. C., for
example, less than 200.degree. C.
[0147] Accordingly, in one embodiment, the glass has a strain point
of 540.degree. C. or greater, for example, 550.degree. C. or
greater, for example, 560.degree. C. or greater, or for example,
from 540.degree. C. to 650.degree. C. In some embodiments, the
glass has a coefficient of thermal expansion of 50.times.10.sup.-7
or greater, for example, 60.times.10.sup.-7 or greater, for
example, 70.times.10.sup.-7 or greater, for example,
80.times.10.sup.-7 or greater. In one embodiment, the glass has a
strain point of from 50.times.10.sup.-7 to 90.times.10.sup.-7.
[0148] In one embodiment, the glass has a coefficient of thermal
expansion of 50.times.10.sup.-7 or greater and a strain point of
540.degree. C. or greater. In one embodiment, the glass has a
coefficient of thermal expansion of 50.times.10.sup.-7 or greater
and a strain point of 560.degree. C. or greater.
[0149] According to one embodiment, the glass is ion exchanged in a
salt bath comprising one or more salts of alkali ions. The glass
can be ion exchanged to change its mechanical properties. For
example, smaller alkali ions, such as lithium can be ion-exchanged
in a molten salt containing one or more larger alkali ions, such as
potassium, rubidium or cesium. If performed at a temperature well
below the strain point for sufficient time, a diffusion profile
will form in which the larger alkali moves into the glass surface
from the salt bath, and the smaller ion is moved from the interior
of the glass into the salt bath. When the sample is removed, the
surface will go under compression, producing enhanced toughness
against damage. Such toughness may be desirable in instances where
the glass will be exposed to adverse environmental conditions, such
as photovoltaic grids exposed to hail. A large alkali already in
the glass can also be exchanged for a smaller alkali in a salt
bath. If this is performed at temperatures close to the strain
point, and if the glass is removed and its surface rapidly reheated
to high temperature and rapidly cooled, the surface of the glass
will show considerable compressive stress introduced by thermal
tempering. This will also provide protection against adverse
environmental conditions. It will be clear to one skilled in the
art that any monovalent cation can be exchanged for alkalis already
in the glass, including copper, silver, thallium, etc., and these
also provide attributes of potential value to end uses, such as
introducing color for lighting or a layer of elevated refractive
index for light trapping.
[0150] According to another embodiment, the glass can be float
formed as known in the art of float forming glass.
[0151] In one embodiment, the glass is in the form of a sheet. The
glass in the form of a sheet can be thermally tempered.
[0152] In one embodiment, an Organic Light Emitting Diode device
comprises the glass in the form of a sheet.
[0153] The glass, according to one embodiment, is transparent.
[0154] In one embodiment, a photovoltaic device comprises the glass
in the form of a sheet. The photovoltaic device can comprise more
than one of the glass sheets, for example, as a substrate and/or as
a superstrate. In one embodiment, the photovoltaic device comprises
the glass sheet as a substrate and/or superstrate, a conductive
material adjacent to the substrate, and an active photovoltaic
medium adjacent to the conductive material. In one embodiment, the
active photovoltaic medium comprises a CIGS layer. In one
embodiment, the active photovoltaic medium comprises a cadmium
telluride (CdTe) layer. In one embodiment, the photovoltaic device
comprises a functional layer comprising copper indium gallium
diselenide or cadmium telluride. In one embodiment, the
photovoltaic device the functional layer is copper indium gallium
diselenide. In one embodiment, the functional layer is cadmium
telluride.
[0155] The photovoltaic device, according to one embodiment,
further comprises a barrier layer disposed between or adjacent to
the superstrate or substrate and the functional layer. In one
embodiment, the photovoltaic device further comprises a barrier
layer disposed between or adjacent to the superstrate or substrate
and a transparent conductive oxide (TCO) layer, wherein the TCO
layer is disposed between or adjacent to the functional layer and
the barrier layer. A TCO may be present in a photovoltaic device
comprising a CdTe functional layer. In one embodiment, the barrier
layer is disposed directly on the glass.
[0156] In one embodiment, the glass sheet is transparent. In one
embodiment, the glass sheet as the substrate and/or superstrate is
transparent.
[0157] According to some embodiments, the glass sheet has a
thickness of 4.0 mm or less, for example, 3.5 mm or less, for
example, 3.2 mm or less, for example, 3.0 mm or less, for example,
2.5 mm or less, for example, 2.0 mm or less, for example, 1.9 mm or
less, for example, 1.8 mm or less, for example, 1.5 mm or less, for
example, 1.1 mm or less, for example, 0.5 mm to 2.0 mm, for
example, 0.5 mm to 1.1 mm, for example, 0.7 mm to 1.1 mm. Although
these are exemplary thicknesses, the glass sheet can have a
thickness of any numerical value including decimal places in the
range of from 0.1 mm up to and including 4.0 mm.
[0158] In one embodiment, an electrochromic device comprises the
glass in the form of a sheet. The electrochromic device can be, for
example, an electrochromic window. In one embodiment, the
electrochromic window comprises one or more of the glass sheets,
such as in a single, double, or triple pane window.
[0159] The fusion-formable glasses of this invention, by virtue of
their relatively high strain point, represent advantaged substrate
materials for CIGS photovoltaic modules as they can enable higher
temperature processing of the critical semiconductor layers. When
manufactured by the fusion process, their superior surface quality
relative to that of float glass may also result in further
improvements to the photovoltaic module making process.
Advantageous embodiments of this invention are characterized by
liquidus viscosity in excess of 400,000 poise, thereby enabling the
fabrication of the relatively thick glass sheet that may be
required by some module manufacturers. Finally, the most
advantageous embodiments of this invention comprise glasses for
which the 200 poise temperature is less than 1580.degree. C.,
providing for the possibility of significantly lower cost
melting/forming.
EXAMPLES
[0160] The following is an example of how to fabricate a sample of
an exemplary glass, according to one embodiment of the invention,
as shown in Table 1. This composition corresponds to composition
number 22 shown in Table 5.
TABLE-US-00001 TABLE 1 oxide mol % SiO.sub.2 64.93 Al.sub.2O.sub.3
0 MgO 17.5 CaO 0 SrO 0 B.sub.2O.sub.3 0 K.sub.2O 17.5 SnO.sub.2
0.10 BaO 0
[0161] In some embodiments, the total does not add up to 100%,
since certain tramp elements are present at non-negligible
concentrations.
[0162] Batch materials, as shown in Table 2 were weighed and added
to a 4 liter plastic container:
TABLE-US-00002 TABLE 2 Batch Components sand Magnesia Potassium
carbonate 10% SnO.sub.2 and 90% sand
[0163] It should be appreciated that in the batch, limestone,
depending on the source can contain tramp elements and/or vary
amounts of one or more oxides, for example, MgO and/or BaO. The
sand is advantageously beneficiated so that at least 80% by mass
passes 60 mesh, for example 80 mesh, for example 100 mesh. The
SnO.sub.2 added, in this example, was pre-mixed with sand at a
level of 10% by weight so as to ensure homogeneous mixing with the
other components. The bottle containing the batch materials was
mounted to a tumbler and the batch materials were mixed so as to
make a homogeneous batch and to break up soft agglomerates. The
mixed batch was transferred to a 1800cc platinum crucible and
placed into a high-temperature ceramic backer. The platinum in its
backer was loaded into a glo-bar furnace idling at a temperature of
1600.degree. C. After 16 hours, the crucible+backer was removed and
the glass melt was poured onto a cold surface, such as a steel
plate, to form a patty, and then transferred to an annealer held at
a temperature of 615.degree. C. The glass patty was held at the
annealer temperature for 2 hours, then cooled at a rate of
1.degree. C. per minute to room temperature. [0062]Table 3, Table
4, Table 5, Table 6, Table 7, Table 8, and Table 9 show exemplary
glasses, according to embodiments of the invention, and made
according to the above example. Properties data for some exemplary
glasses are also shown in Table 3, Table 4, Table 5, Table 6, Table
7, Table 8, and Table 9.
[0164] In the Tables I.sub.str(.degree. C.) is the strain point
which is the temperature when the viscosity is equal to 10.sup.14.7
P as measured by beam bending or fiber elongation.
T.sub.ann(.degree. C.) is the annealing point which is the
temperature when the viscosity is equal to 10.sup.13.18 P as
measured by beam bending or fiber elongation. T.sub.s(.degree. C.)
is the softening point which is the temperature when the viscosity
is equal to 10.sup.7.6 P as measured by beam bending or fiber
elongation. .alpha.(10.sup.-7/.degree. C.) or a(10.sup.-7/.degree.
C.) in the Tables is the coefficient of thermal expansion (CTE)
which is the amount of dimensional change from either 0 to
300.degree. C. or 25 to 300.degree. C. depending on the
measurement. CTE is typically measured by dilatometry. r(g/cc) is
the density which is measured with the Archimedes method (ASTM
C693). T.sub.200(.degree. C.) is the two-hundred Poise (P)
temperature. This is the temperature when the viscosity of the melt
is 200P as measured by HTV (high temperature viscosity) measurement
which uses concentric cylinder viscometry. T.sub.liq(.degree. C.)
is the liquidus temperature. This is the temperature where the
first crystal is observed in a standard gradient boat liquidus
measurement (ASTM C829-81). Generally this test is 72 hours but can
be as short as 24 hours to increase throughput at the expense of
accuracy (shorter tests could underestimate the liquidus
temperature). .eta..sub.liq(.degree. C.) is the liquidus viscosity.
This is the viscosity of the melt corresponding to the liquidus
temperature.
TABLE-US-00003 TABLE 3 Example 1 2 3 4 5 6 7 8 9 10 Composition
(mol %) K.sub.2O 3 4.5 6 4.95 12.1 12.1 12 12 12 10 MgO 0 0 0 0 1.7
3.38 3.8 4.4 4 5.2 CaO 0 0 0 0 6.76 3.38 3.8 4.4 4 5.2 SrO 0.41
0.31 0.21 0.28 0 1.7 1.9 2.2 2 2.6 BaO 20.29 15.19 10.12 13.67 0 0
0 0 0 0 B.sub.2O.sub.3 18.67 14 9.33 12.6 3.03 3.03 3 1.5 1.5 1.5
Al.sub.2O.sub.3 3 4.5 6 4.95 4.88 4.88 4 4 5 4 SiO.sub.2 54.67 61.5
68.33 63.55 71.43 71.43 71.4 71.4 71.4 71.4 SnO.sub.2 0 0 0 0.1 0.1
0.1 0.1 0.1 0.1 0.1 Composition (wt %) K.sub.2O 3.4 5.35 7.52 5.97
17.2 17.1 17.1 17.1 17 14.4 MgO 0 0 0 0 1.04 2.05 2.32 2.68 2.43
3.2 CaO 0 0 0 0 5.73 2.84 3.21 3.73 3.37 4.46 SrO 0.51 0.41 0.29
0.37 0 2.64 2.97 3.44 3.11 4.12 BaO 37.3 29.4 20.7 26.9 0 0 0 0 0 0
B.sub.2O.sub.3 15.6 12.3 8.64 11.2 3.18 3.16 3.15 1.58 1.57 1.6
Al.sub.2O.sub.3 3.68 5.79 8.14 6.46 7.53 7.46 6.16 6.17 7.66 6.24
SiO.sub.2 39.4 46.6 54.6 48.9 64.9 64.3 64.7 64.9 64.5 65.6
SnO.sub.2 0 0 0 0.19 0.23 0.23 0.23 0.23 0.23 0.23 T.sub.str
(.degree. C.) 578 ~580 584 588 597 591 591 595 604 606 T.sub.ann
(.degree. C.) 616 ~620 627 625 644 640 638 645 655 657 T.sub.s
(.degree. C.) 754 770 815 790 a (10.sup.-7/.degree. C.) 71.9 70.6
65.3 66.8 79.9 79.6 80.2 82.5 80.5 76 r (gm/cc) 2.901 2.446 2.462
2.472 2.483 2.473 2.493 T.sub.200 (.degree. C.) 1111 1254 1443 1410
1595 1624 1589 1617 1622 1613 T.sub.liq (.degree. C.) 885 905 910
910 1060 975 950 995 1085 1050 .eta..sub.liq (kp) 37 110 724 235
129 1221 1675 910 156 298
TABLE-US-00004 TABLE 4 Example 11 12 13 14 15 16 17 18 19 20
Composition (mol %) K.sub.2O 12 12 12 12 10 12 12 12 12 12 MgO 3.4
3 4.2 4.8 5.6 4 4.4 5 3.67 1.84 CaO 3.4 3 4.2 4.8 5.6 4 4.4 5 5.5
7.33 SrO 1.7 1.5 2.1 2.4 2.8 2 2.2 2.5 1.82 1.82 BaO 0 0 0 0 0 0 0
0 0.01 0.01 B.sub.2O.sub.3 4 4 3 1.5 1.5 4 3 1.5 1.5 1.5
Al.sub.2O.sub.3 4 5 3 3 3 2.5 2.5 2.5 4 4 SiO.sub.2 71.4 71.4 71.4
71.4 71.4 71.4 71.4 71.4 71.4 71.4 SnO.sub.2 0.1 0.1 0.1 0.1 0.1
0.1 0.1 0.1 0.1 0.1 Composition (wt %) K.sub.2O 17 16.9 17.2 17.2
14.5 17.2 17.2 17.3 17.1 17 MgO 2.07 1.81 2.57 2.94 3.47 2.46 2.7
3.07 2.24 1.12 CaO 2.87 2.52 3.57 4.1 4.83 3.41 3.76 4.28 4.67 6.2
SrO 2.65 2.33 3.3 3.78 4.46 3.15 3.47 3.95 2.86 2.85 BaO 0 0 0 0 0
0 0 0 0.02 0.02 B.sub.2O.sub.3 4.19 4.17 3.17 1.59 1.61 4.23 3.18
1.6 1.58 1.58 Al.sub.2O.sub.3 6.15 7.64 4.64 4.65 4.71 3.87 3.88
3.89 6.17 6.15 SiO.sub.2 64.6 64.2 65.1 65.3 66 65.3 65.4 65.6 65
64.7 SnO.sub.2 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23
T.sub.str (.degree. C.) 585 590 585 592 602 582 586 588 598 600
T.sub.ann (.degree. C.) 632 638 631 640 651 627 632 636 647 648
T.sub.s (.degree. C.) a (10.sup.-7/.degree. C.) 79.4 78.1 79.5 83.8
77 81.9 81.5 84.4 82 84.2 r (gm/cc) 2.466 2.451 2.483 2.494 2.502
2.485 2.489 2.497 2.478 2.492 T.sub.200 (.degree. C.) 1596 1625
1553 1553 1556 1527 1508 1523 1585 1549 T.sub.liq (.degree. C.)
<900 940 <950 960 1040 <850 870 940 985 1030 .eta..sub.liq
(kp) >2000 2143 >1000 1080 202 >7000 6297 1385 660 179
TABLE-US-00005 TABLE 5 Example 21 22 23 24 25 26 27 28 29 30
Composition (mol %) K.sub.2O 12 17.5 14.94 10.8 9.6 12.47 13.6 12.6
13.35 11.77 MgO 1.83 17.5 1.37 5.17 4.59 11.02 12.9 13.9 13.7 11.94
CaO 5.5 0 1.11 6.21 10.18 3.13 2.4 2.4 1.75 0.86 SrO 3.65 0 0.77
1.4 1.24 1.01 1.45 1.45 1.1 0.66 BaO 0.02 0 0 0 0 0 0 0 0 3.04
B.sub.2O.sub.3 1.5 0 0.4 3.52 6.24 1.64 0.4 0.4 1.9 3.11
Al.sub.2O.sub.3 4 0 4.17 4.32 3.84 3.13 2.35 2.35 2.3 2.76
SiO.sub.2 71.4 64.93 77.17 68.51 64.24 67.53 66.8 66.8 65.8 65.79
SnO.sub.2 0.1 0.07 0.07 0.07 0.07 0.07 0.1 0.1 0.1 0.07 Composition
(wt %) K.sub.2O 16.8 26.3 21 15.6 13.9 18.3 20 18.7 19.7 16.7 MgO
1.1 11.2 0.82 3.18 2.85 6.93 8.13 8.83 8.67 7.24 CaO 4.59 0 0.93
5.32 8.78 2.73 2.11 2.13 1.54 0.73 SrO 5.63 0 1.19 2.22 1.98 1.64
2.34 2.36 1.79 1.03 BaO 0.05 0 0 0 0 0 0 0 0 7.02 B.sub.2O.sub.3
1.56 0 0.42 3.74 6.69 1.78 0.44 0.44 2.08 3.25 Al.sub.2O.sub.3 6.07
0 6.33 6.73 6.03 4.98 3.74 3.78 3.68 4.23 SiO.sub.2 63.8 62.1 69
62.9 59.4 63.3 62.8 63.3 62.1 59.5 SnO.sub.2 0.22 0.17 0.16 0.16
0.16 0.16 0.24 0.24 0.24 0.16 T.sub.str (.degree. C.) 593 610 565
592 594 595 594 602 592 576 T.sub.ann (.degree. C.) 641 661 616 638
634 647 649 656 641 624 T.sub.s (.degree. C.) 879 847 847 815 866
874 879 858 835 a (10.sup.-7/.degree. C.) 84 104.1 88.6 78 77.8 85
89.9 85.7 87.9 83.7 r (gm/cc) 2.523 2.444 2.418 2.483 2.512 2.472
2.483 2.485 2.468 2.558 T.sub.200 (.degree. C.) 1547 1535 1531 1502
1473 T.sub.liq (.degree. C.) 1010 <1150 <950 1050 1080 1075
1080 1080 1060 990 .eta..sub.liq (kp) 251 103 109 ~75 ~86 106
290
TABLE-US-00006 TABLE 6 Example 31 32 33 34 35 36 37 38 39 40
Composition (mol %) K.sub.2O 14 12 11.76 11.73 10.96 16 14.61 12.19
14.1 14.1 MgO 2.9 3.9 3.82 6.57 6.14 0 1.38 3.79 1.33 0 CaO 2.85
3.65 3.58 5.77 5.39 5 5.32 5.89 5.14 5.13 SrO 0.7 0.9 0.88 1.88
1.75 0 0 1.03 0 1.33 BaO 0 0 0 0 0 0 0 0 0 0 B.sub.2O.sub.3 3.03
3.03 5 1.55 1.45 3 3.14 3.38 3.03 3.03 Al.sub.2O.sub.3 4.9 4.9 4.8
2.91 2.72 5.34 5.06 4.59 4.89 4.88 SiO.sub.2 71.52 71.52 70.06 69.5
71.5 70.56 70.39 69.06 71.49 71.42 SnO.sub.2 0.1 0.1 0.1 0.1 0.1 0
0.1 0.1 0.1 0.1 Composition (wt %) K.sub.2O 19.7 17.1 16.7 17 16
22.2 20.5 17.4 19.9 19.6 MgO 1.75 2.38 2.33 4.07 3.83 0 0.83 2.31
0.8 0 CaO 2.39 3.09 3.02 4.98 4.67 4.13 4.45 4.99 4.31 4.25 SrO
1.08 1.41 1.38 2.99 2.8 0 0 1.62 0 2.04 BaO 0 0 0 0 0 0 0 0 0 0
B.sub.2O.sub.3 3.14 3.18 5.25 1.66 1.56 3.07 3.26 3.55 3.16 3.12
Al.sub.2O.sub.3 7.46 7.55 7.39 4.57 4.29 8 7.69 7.07 7.45 7.36
SiO.sub.2 64.1 64.9 63.5 64.3 66.4 62.4 62.8 62.7 64.2 63.4
SnO.sub.2 0.23 0.23 0.23 0.23 0.23 0 0.23 0.23 0.22 0.21 T.sub.str
(.degree. C.) 597 613 608 598 607 565 588 594 595 590 T.sub.ann
(.degree. C.) 645 663 658 646 658 611 633 640 640 635 T.sub.s
(.degree. C.) a (10.sup.-7/.degree. C.) 84.8 78.1 74.7 85.1 81.1 90
88 82.3 86.1 86 r (gm/cc) 2.446 2.441 2.434 2.498 2.48 2.452 2.473
2.446 2.475 T.sub.200 (.degree. C.) 1624 1649 1648 1515 1557 1554
1558 1594 1567 T.sub.liq (.degree. C.) 1010 1010 960 1010 1010 1010
1040 1035 990 980 .eta..sub.liq (kp) 376 886 2729 270 479 105 169
394 407
TABLE-US-00007 TABLE 7 Example 41 42 43 44 45 46 47 48 49
Composition (mol %) K.sub.2O 12.37 10.32 11.97 13.21 9.21 12.37 4 8
5 MgO 1.17 1.16 1.33 1.24 0 1.17 1.75 12 4 CaO 4.51 4.49 2.13 4.81
5.14 4.51 7.02 1 7 SrO 0 1.18 2.99 0 4.14 0 2.91 7 1 BaO 0 1.18
1.69 0 2 0 3.32 7 12 B.sub.2O.sub.3 2.66 2.64 2.99 2.84 3.03 3.36
10.67 1 0 Al.sub.2O.sub.3 4.28 4.26 4.99 4.58 4.89 4.28 8.52 0 0
SiO.sub.2 75.01 74.65 71.81 73.23 71.49 74.01 62.25 64 71 SnO.sub.2
0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Composition (wt %) K.sub.2O
17.6 14.5 16.3 18.7 12.5 17.6 5.36 10.7 6.5 MgO 0.71 0.7 0.77 0.75
0 0.71 1.01 6.89 2.22 CaO 3.82 3.75 1.73 4.05 4.16 3.82 5.6 0.8
5.41 SrO 0 1.83 4.47 0 6.2 0 4.3 10.3 1.43 BaO 0 2.71 3.73 0 4.43 0
7.24 15.3 25.4 B.sub.2O.sub.3 2.8 2.75 3.01 2.97 3.05 3.54 10.6
0.99 0 Al.sub.2O.sub.3 6.59 6.48 7.34 7.02 7.2 6.6 12.4 0 0
SiO.sub.2 68.1 66.9 62.3 66.1 62.1 67.3 53.2 54.7 58.8 SnO.sub.2
0.23 0.22 0.22 0.23 0.22 0.23 0.21 0.21 0.21 T.sub.str (.degree.
C.) 602 604 592 599 623 603 582 608 T.sub.ann (.degree. C.) 651 653
639 647 672 651 628 656 T.sub.s (.degree. C.) a (10.sup.-7/.degree.
C.) 74.2 74.2 81.3 81.2 73.5 78.1 88.9 73 r (gm/cc) 2.424 2.485
2.451 2.435 2.585 2.428 2.889 2.933 T.sub.200 (.degree. C.) 1637
1669 1586 1611 1613 1615 1491 1347 1406 T.sub.liq (.degree. C.) 800
940 980 945 1090 960 1000 1005 .eta..sub.liq (kp) 427,000 4527 301
1829 107 665 59 156
TABLE-US-00008 TABLE 8 Example 50 51 52 53 54 55 56 Composition
(mol %) K.sub.2O 11.79 11.91 12.04 11.25 8.96 10.9 10.79 MgO 6.03
4.95 3.87 6.3 7.06 6.11 6.05 CaO 5.64 5.39 5.13 5.53 6.21 5.36 5.31
SrO 1.69 1.32 0.94 1.8 2.01 1.74 1.72 BaO 0 0 0 0 0 0 0
B.sub.2O.sub.3 1.66 1.88 2.11 5.55 1.45 1.44 2.44 Al.sub.2O.sub.3
3.05 3.32 3.6 2.79 2.72 3.22 3.19 SiO.sub.2 70.04 71.13 72.21 66.68
71.5 71.13 70.4 SnO.sub.2 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Composition
(wt %) K.sub.2O 17.06 17.18 17.3 16.27 13.22 15.84 15.66 MgO 3.73
3.05 2.38 3.9 4.45 3.8 3.76 CaO 4.86 4.63 4.39 4.76 5.45 4.63 4.59
SrO 2.69 2.1 1.49 2.86 3.26 2.78 2.74 BaO 0 0 0 0 0 0 0
B.sub.2O.sub.3 1.78 2.01 2.25 5.93 1.58 1.55 2.62 Al.sub.2O.sub.3
4.78 5.18 5.6 4.36 4.34 5.06 5.01 SiO.sub.2 64.66 65.43 66.18 61.49
67.27 65.91 65.19 SnO.sub.2 0.23 0.23 0.23 0.23 0.24 0.23 0.23
T.sub.str (.degree. C.) 596 597 601 612 627 624 622 T.sub.ann
(.degree. C.) 645 646 651 660 679 671 674 T.sub.s (.degree. C.) a
(10.sup.-7/.degree. C.) 83.3 82.6 82.5 71.9 72.4 78.3 74.9 r
(gm/cc) 2.486 2.473 2.458 2.48 2.483 2.477 2.473 T.sub.200
(.degree. C.) 1543 1560 1608 1557 1560 1576 1613 T.sub.liq
(.degree. C.) 995 985 950 1080 1095 1020 1055 .eta..sub.liq (kp)
480 688 2361 76 96 553 329
TABLE-US-00009 TABLE 9 Example 57 58 59 60 61 62 63 Composition
(mol %) K.sub.2O 10.15 9.95 3.35 3.75 4.1 3.64 10.1 MgO 5.69 5.58
5.39 6.04 6.59 5.87 5.66 CaO 4.99 4.89 5.57 6.24 6.81 6.06 4.96 SrO
1.62 1.59 2.3 2.58 2.81 2.51 1.61 BaO 0 2 0 0 0 0 0 B.sub.2O.sub.3
1.34 1.31 5.69 5.69 5.69 5.53 1.33 Al.sub.2O.sub.3 3 2.94 11.26
10.46 9.78 10.16 3.5 SiO.sub.2 73.11 71.64 66.37 65.17 64.15 66.17
72.74 SnO.sub.2 0.1 0.1 0.07 0.07 0.07 0.07 0.1 total 100 100 100
100 100 100.01 100 Composition (wt %) K.sub.2O 14.82 14.14 4.75
5.34 5.86 5.2 14.7 MgO 3.55 3.39 3.27 3.68 4.03 3.58 3.52 CaO 4.34
4.13 4.7 5.29 5.79 5.15 4.3 SrO 2.61 2.49 3.59 4.04 4.41 3.94 2.58
BaO 0 4.62 0 0 0 0 0 B.sub.2O.sub.3 1.45 1.38 5.97 5.99 6.01 5.84
1.43 Al.sub.2O.sub.3 4.74 4.52 17.3 16.12 15.15 15.7 5.51 SiO.sub.2
68.09 64.94 60.09 59.2 58.44 60.26 67.54 SnO.sub.2 0.23 0.23 0.16
0.16 0.16 0.16 0.23 total 99.83 99.84 99.83 99.82 99.85 99.83 99.81
Tstr (.degree. C.) 609 598 660 645 632 645 621 Tann (.degree. C.)
658 645 714 694 678 694 671 Ts (.degree. C.) a (10-7/.degree. C.)
76.2 79.7 46.7 52.8 55.5 50 75 r (gm/cc) 2.462 2.544 2.463 2.504
2.517 2.474 2.46 T200 (.degree. C.) 1605 1569 1609 1597 1555 1600
1613 Tliq (.degree. C.) 1000 950 1110 1080 1080 1065 1025 nliq (kp)
967 2257 287 432 228 695 682
[0165] It will be apparent to those skilled in the art that various
modifications and variations can be made to the present invention
without departing from the spirit or scope of the invention. Thus,
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *