阅读说明：本技术 光敏玻璃和玻璃陶瓷以及由它们制成的复合玻璃材料 (Photosensitive glass and glass ceramic and composite glass material made of them ) 是由 乔治·哈尔西·北奥 古拉斯·弗朗西斯·博雷利 约瑟夫·弗朗西斯·施罗德三世 托马斯·飞利浦·西 于 2017-01-26 设计创作，主要内容包括：提供了可经选择性地辐照和陶瓷化以提供玻璃和锂基玻璃陶瓷的图案化区域的光敏铝硅酸锂锌玻璃,和由此类玻璃和玻璃陶瓷制成的复合玻璃制品。锂基玻璃陶瓷和铝硅酸锂锌玻璃的界面处的压缩和拉伸应力可以用于抵制这种复合玻璃/玻璃陶瓷制品中的裂纹传播。还提供了制造包括此类锂基玻璃陶瓷和铝硅酸锂锌玻璃的复合玻璃制品的方法。(Photosensitive lithium zinc aluminosilicate glasses that can be selectively irradiated and cerammed to provide patterned regions of glass and lithium-based glass-ceramics, and composite glass articles made from such glasses and glass-ceramics, are provided. Compressive and tensile stresses at the interface of the lithium-based glass ceramic and the lithium zinc aluminosilicate glass can be used to resist crack propagation in such composite glass/glass ceramic articles. Methods of making composite glass articles comprising such lithium-based glass-ceramics and lithium zinc aluminosilicate glasses are also provided.)

1. A composite glass article comprising a first region and a second region in contact with the first region at an interface, the first region comprising a lithium-based glass-ceramic comprising a ceramic phase and a residual glass phase, wherein the ceramic phase comprises a lithium aluminosilicate phase having a lithium aluminosilicate-loaded β -quartz structure, and the second region comprising a lithium zinc aluminosilicate glass, wherein the lithium zinc aluminosilicate glass is transparent, comprises at least one sensitizer and at least one nucleating agent, and is positively photosensitive to ultraviolet radiation.

2. The composite glass article of claim 1, wherein the first region is spatially separated from the second region.

3. The composite glass article of claim 1 or 2, wherein the lithium-based glass ceramic is under a compressive stress at an interface between the lithium-based glass ceramic and the lithium zinc aluminosilicate glass, and the lithium zinc aluminosilicate glass is under a tensile stress at the interface.

4. The composite glass article of any of claims 1-3, wherein the at least one sensitizer comprises at least one of silver and cerium.

5. The composite glass article of any of claims 1-4, wherein the at least one nucleating agent comprises at least one halogen.

6. The composite glass article of claim 5, wherein the at least one halogen comprises at least one of fluorine, bromine, and chlorine.

7. The composite glass article of any of claims 1-6, wherein the lithium zinc aluminosilicate glass comprises: from about 68% to about 78% by weight SiO₂(ii) a Up to about 1 wt.% K₂O; from about 5% to about 10% by weight ZnO; up to about 10 wt% Br^-(ii) a From about 5 wt.% to about 14 wt.% Al₂O₃(ii) a From about 0.01 wt.% to about 0.07 wt.% CeO₂(ii) a From about 0.01 wt% to about 0.05 wt% Ag; from about 5 wt% to about 10 wt% Li₂O; up to about 1% by weight Na₂O; from about 0 wt.% to about 3 wt.% F^-(ii) a And up to about 5 wt% ZrO₂。

8. The composite glass article of any of claims 1-6, wherein the lithium zinc aluminosilicate glass comprises: from about 72 wt.% to about 76 wt.% SiO₂(ii) a From about 0.5% to about 1% by weight of K₂O; from about 5% to about 7% by weight ZnO; from about 0.5 wt.% to about 0.8 wt.% Br^-(ii) a From about 6 to about 8 weight percent Al₂O₃(ii) a From about 0.01 wt.% to about 0.04 wt.% CeO₂(ii) a From about 0.03 wt% to about 0.05 wt% Ag; from about 6 to about 8 weight percent Li₂O; up to about 0.05 wt.% Na₂O; from about 2 to about 3 weight percent F^-(ii) a And from about 0.5 wt.% to about 5 wt.% ZrO₂。

9. The composite glass article of any of claims 1-6, wherein the lithium zinc aluminosilicate glass comprises: from about 68 to about 77 wt% SiO₂(ii) a From about 0.5% to about 1% by weight of K₂O; from about 6% to about 10% by weight ZnO; from about 0.5 wt.% to about 1.0 wt.% Br^-(ii) a From about 7 wt.% to about 10 wt.% Al₂O₃(ii) a From about 0.02 wt.% to about 0.05 wt.% CeO₂(ii) a From about 0.02 wt% to about 0.05 wt% Ag; from about 7 wt.% to about10% by weight of Li₂O; up to about 0.05 wt.% Na₂O; from about 1% to about 3% by weight of F^-(ii) a And up to about 4 wt% ZrO₂。

10. The composite glass article of any of claims 1-6, wherein the lithium zinc aluminosilicate glass comprises: from about 70 wt.% to about 78 wt.% SiO₂(ii) a From about 0.5% to about 1% by weight of K₂O; from about 5% to about 7% by weight ZnO; from about 0 wt.% to about 10 wt.% Br^-(ii) a From about 6 to about 8 weight percent Al₂O₃(ii) a From about 0.02 wt.% to about 0.05 wt.% CeO₂(ii) a From about 0.02 wt% to about 0.05 wt% Ag; from about 6 to about 8 weight percent Li₂O; up to about 1% by weight Na₂O; and from 0 wt% to about 3 wt% of F^-。

11. The composite glass article of any of claims 1-10, wherein the glass-ceramic is Na-free₂O、MgO、P₂O₅、TiO₂、ZrO₂And bromine.

12. The composite glass article of any of claims 1-11, wherein the lithium aluminosilicate phase comprises at least 50 vol% of the lithium-based glass-ceramic.

13. A method of making a composite glass article comprising a lithium zinc aluminosilicate glass and a lithium based glass-ceramic, the lithium based glass-ceramic comprising a ceramic phase and a residual glass phase, the ceramic phase comprising a lithium aluminosilicate phase, the lithium aluminosilicate phase having a lithium aluminosilicate β quartz structure, the method comprising the steps of:

a. providing a lithium zinc aluminosilicate precursor glass comprising at least one sensitizer and at least one nucleating agent, wherein the lithium zinc aluminosilicate glass is positively photosensitive;

b. exposing a first region of the lithium zinc aluminosilicate precursor glass to ultraviolet radiation having a wavelength in a range from about 248nm to about 360nm, while a second region of the lithium zinc aluminosilicate glass is not exposed to the ultraviolet radiation;

c. heating the lithium zinc aluminosilicate precursor glass at a first temperature for a first period of time to reduce silver; and

d. heating the lithium zinc aluminosilicate precursor glass at a second temperature for a second period of time to form the lithium-based glass-ceramic in the first region to form the composite glass article.

14. The method of claim 13, wherein the first temperature is in a range from about 550 degrees celsius to about 675 degrees celsius and the first period of time is in a range from about 0.5 hours to about 4 hours; and is

The second temperature is in a range from about 550 degrees Celsius to about 675 degrees Celsius, and the second period of time is in a range from about 0.5 hours to about 4 hours.

15. The method of claim 13 or 14, wherein the lithium zinc aluminosilicate precursor glass comprises: from about 68% to about 78% by weight SiO₂(ii) a Up to about 1 wt.% K₂O; from about 5% to about 10% by weight ZnO; up to about 10 wt% Br^-(ii) a From about 5 wt.% to about 14 wt.% Al₂O₃(ii) a From about 0.01 wt.% to about 0.07 wt.% CeO₂(ii) a From about 0.01 wt% to about 0.05 wt% Ag; from about 5 wt% to about 10 wt% Li₂O; up to about 1% by weight Na₂O; from about 0 wt.% to about 3 wt.% F^-(ii) a And up to about 5 wt% ZrO₂。

Background

The present disclosure relates to photosensitive glass. More particularly, the present disclosure relates to photosensitive glasses that can be processed to form glass-ceramics. More particularly, the present disclosure relates to photosensitive lithium-zinc-aluminosilicate glasses and glass-ceramics that can include both transparent and opaque or translucent (i.e., proteolitic) regions.

Glass-ceramics are nominally manufactured by thermal processes in which the as-manufactured glass is heat treated to produce a controlled crystalline phase. Cerium and silver sensitizers have been used in glass systems, such as FOTOFORM^TMAnd FOTA-LITE^TMTo produce a photosensitive material having a crystal content well below the 50% level typically defining glass-ceramics. In such glass systems, NaF containing an opal (i.e., opaque, light dense, white, light scattering) phase forms in the regions of the glass that are exposed to short wavelength light and subsequently heat treated, while the unexposed regions of the glass remain clear.

Disclosure of Invention

Photosensitive lithium zinc aluminosilicate glasses that can be selectively cerammed to provide patterned regions of glass and glass-ceramics, and composite glass articles made from such glasses and glass-ceramics, are provided. When these glasses are exposed to Ultraviolet (UV) radiation and heat treatment (ceramming), lithium-based glass-ceramics having a beta-quartz crystal structure are formed in selected regions of the glass. In some embodiments, the lithium zinc aluminosilicate glass is "negative" photosensitive; that is, the lithium-based glass-ceramic forms in portions of the glass that are not exposed or shielded from ultraviolet radiation, while the transparent lithium zinc aluminosilicate glass remains in those areas exposed to ultraviolet radiation. In other embodiments, the lithium zinc aluminosilicate glass is "positive" photosensitive; that is, the lithium-based glass-ceramic is formed in the portions of the glass that are exposed to ultraviolet radiation, while the transparent lithium zinc aluminosilicate glass remains in those regions that are not exposed to ultraviolet radiation. In some embodiments, the lithium-based glass-ceramic is "proteolitized"; i.e., opaque or translucent, or in some embodiments milky white. Compressive and tensile stresses at the interface of the lithium-based glass ceramic and the lithium zinc aluminosilicate glass can be used to resist crack propagation in such composite glass/glass ceramic articles. Methods of making composite glass articles comprising such lithium-based glass-ceramics and lithium zinc aluminosilicate glasses are also provided.

Accordingly, one aspect of the present disclosure is to provide a composite glass article comprising a first region and a second region. The first region includes a lithium-based glass-ceramic. The lithium-based glass-ceramic includes a residual glass phase and a ceramic phase, the ceramic phase including a lithium aluminosilicate phase having a lithium aluminosilicate packed beta quartz structure. The second region comprises a lithium zinc aluminosilicate glass comprising at least one sensitizer and at least one nucleating agent. The lithium zinc aluminosilicate glass is photosensitive to ultraviolet radiation having a wavelength in the range of about 248nm to about 360 nm.

A second aspect of the present disclosure is to provide a lithium zinc aluminosilicate glass comprising at least one sensitizer and at least one nucleating agent, wherein the lithium zinc aluminosilicate glass is photosensitive to radiation having a wavelength in the range of about 248nm to about 360 nm.

A third aspect of the present disclosure is to provide a method of making a composite glass article comprising a lithium zinc aluminosilicate glass and a lithium-based glass ceramic. The lithium-based glass-ceramic includes a residual glass phase and a ceramic phase, wherein the ceramic phase includes a lithium aluminosilicate phase having a lithium aluminosilicate beta quartz structure. The method comprises the following steps: providing a lithium zinc aluminosilicate precursor glass comprising at least one sensitizer and at least one nucleating agent, wherein the lithium zinc aluminosilicate glass is negatively photosensitive; exposing a first region of a lithium zinc aluminosilicate precursor glass to ultraviolet radiation having a wavelength in a range from about 248nm to about 360nm, wherein a second region of the lithium zinc aluminosilicate precursor glass is not exposed to the ultraviolet radiation; and heating the exposed lithium zinc aluminosilicate precursor glass to form a lithium-based glass-ceramic in the second region.

A fourth aspect of the present disclosure is to provide a method of making a composite glass article comprising a lithium zinc aluminosilicate glass and a lithium-based glass ceramic. The lithium-based glass-ceramic includes a residual glass phase and a ceramic phase, wherein the ceramic phase includes a lithium aluminosilicate phase having a lithium aluminosilicate β quartz structure, and the lithium-based glass-ceramic includes the residual glass phase. The method comprises the following steps: providing a lithium zinc aluminosilicate precursor glass comprising at least one sensitizer and at least one nucleating agent, wherein the lithium zinc aluminosilicate glass is negatively photosensitive; exposing a first region of a lithium zinc aluminosilicate precursor glass to ultraviolet radiation having a wavelength in a range from about 248nm to about 360nm, wherein a second region of the lithium zinc aluminosilicate precursor glass is not exposed to the ultraviolet radiation; heating a lithium zinc aluminosilicate precursor glass at a first temperature for a first period of time; and heating the lithium zinc aluminosilicate precursor glass at a second temperature for a second period of time to form a lithium-based glass-ceramic in the first region.

These and other aspects, advantages, and salient features will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

Brief Description of Drawings

FIG. 1 is a photograph of a positive photosensitive lithium zinc aluminosilicate precursor glass/glass ceramic sample, in which ZrO is present₂Adding to a negative photosensitive lithium aluminosilicate zinc precursor glass composition;

FIG. 2 is an X-ray diffraction pattern obtained for a proteolization portion of a sample, exposed to ultraviolet radiation, first heat treated at 575 degrees Celsius for two hours, cooled to room temperature, and then heat treated at 575 degrees Celsius for two hours;

FIG. 3 is a photograph of two samples after exposure to ultraviolet radiation and heat treatment at a first temperature and a second temperature;

FIG. 4 is a photograph of two samples after exposure to ultraviolet radiation and heat treatment at a first temperature and a second temperature;

FIG. 5A is a graph of thermal expansion of a lithium-based glass ceramic of a composite glass article described herein as a function of temperature;

FIG. 5B is a graph of thermal expansion as a function of temperature for lithium zinc aluminosilicate glasses described herein;

fig. 6 shows microscopic images of the composite glass article under unpolarized light (a) and under polarized light (B);

FIG. 7 is a photograph showing internal stresses generated in a patterned composite glass article comprising a ortho-photosensitive lithium zinc aluminosilicate glass and a lithium-based glass ceramic described herein;

FIG. 8 is a schematic view of a patterned composite glass article described herein;

FIG. 9 is a flow chart depicting a method for making a composite glass article using a negative photosensitive lithium zinc aluminosilicate precursor glass; and

FIG. 10 is a flow chart depicting a method for making a composite glass article using an ortho-photosensitive lithium zinc aluminosilicate precursor glass.

Detailed Description

In the following description, like reference characters designate like or corresponding parts throughout the several views shown in the figures. It will also be understood that terms such as "top," "bottom," "outward," "inward," and the like are words of art and are not to be construed as limiting terms unless otherwise specified. Additionally, whenever a group is described as including at least one element and a combination of elements from a set of elements, it is understood that the group may include, consist essentially of, or consist of: any number of those elements, alone or in combination with one another. Similarly, whenever a group is referred to as being made up of at least one element and combinations of elements in a set of elements, it is understood that the group may be made up of any number of those elements alone or in combination with one another. Unless otherwise specified, a range of values, when recited, includes the upper and lower limits of the range, and any range between the stated ranges. As used herein, the indefinite articles "a", "an", and the corresponding definite article "the" mean "at least one" or "one or more", unless otherwise specified. It should also be understood that the various features disclosed in this specification and the drawings may be used in any and all combinations.

As used herein, the terms "composite glass article" and "composite glass-ceramic article" are used in their broadest sense to include any article made in whole or in part from glass and glass-ceramic. All compositions are expressed as weight percent (wt%), unless otherwise specified. As used herein, the terms "ceramic" and "ceramization" refer to a thermal treatment or process in which a precursor glass is converted to a glass-ceramic.

As used herein, the term "glass-ceramic" refers to a material comprising a glass phase and a crystalline ceramic phase, wherein the ceramic phase occupies or comprises at least 50% by volume of the material. The terms "glass-ceramic" and "crystalline" are equivalent terms and are used interchangeably herein.

As used herein, the term "opal" refers to an opaque, optically dense, white, and/or light-scattering glass, ceramic, or glass-ceramic material that may, but need not, have opalescent properties. The term "proteolization" refers to the process of converting glass, ceramic or glass-ceramic materials into a proteinic material. The opal or proteinpetrochemicals material comprises at least one crystalline or ceramic phase in which crystalline particles have an average particle size in or above the visible wavelength range (400nm to 750 nm). As used herein, the term "translucent" refers to a material that transmits and diffuses light such that objects on the other side of the material are not clearly visible to the naked eye.

As used herein, the terms "inverse photosensitive", "negative photosensitive" and "negative photosensitive" refer to a material and process that leaves the area of the material exposed to electromagnetic radiation clear, while the unexposed remainder of the material becomes proteolitized or translucent when the material is subsequently heated at a temperature above room temperature. Conversely, the terms "positive photosensitive" and "positive photosensitive" refer to a material and process that causes the areas of the material exposed to electromagnetic radiation to become proteolitic or translucent while the unexposed remainder of the material remains clear.

It should be noted that the terms "substantially" and "about" may be used herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. Such terms are also used herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. Thus, for example, considered "substantially free of TiO₂Or does not contain TiO₂"is a glass of this kind: not adding TiO₂With active addition or batchwise addition of glass, but TiO₂May be present in very small amounts (e.g., ≦ 100ppm, or in some embodiments ≦ 50ppm) as contaminants.

With general reference to the drawings, it will be understood that the illustrations are for the purpose of describing particular embodiments only, and are not intended to limit the scope of the present disclosure or the appended claims. The drawings are not necessarily to scale and certain features and certain views of the drawings may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.

In one aspect, a photosensitive lithium zinc aluminosilicate glass is provided. The glass comprises at least one sensitizer and at least one nucleating agent. Lithium zinc aluminosilicate glass is photosensitive to Ultraviolet (UV) radiation having a wavelength in the range of about 248nm to about 360 nm. In some embodiments, the at least one sensitizer may include, but is not limited to, at least one of silver and cerium. The at least one nucleating agent may include, but is not limited to, silver and/or at least one halogen or halide. In some embodiments, the at least one nucleating agent comprises at least one of fluorine, chlorine and bromine. In certain embodiments, the at least one nucleating agent comprises fluorine and/or bromine.

In some embodiments, the photosensitive lithium zinc aluminosilicate glass is negatively photosensitive; that is, the areas of the material that are exposed to ultraviolet radiation and subsequently heat treated or cerammed remain transparent, while the remainder of the material that is not exposed to or shielded from such radiation and subsequently heat treated at a temperature of at least about 500 degrees celsius becomes proteolitized or translucent. In such embodiments, the photosensitive glass includes a nucleating agent and a sensitizer, such as, but not limited to, fluorine. Silver, which acts as a nucleating agent in the exposed portion of the glass, has a face-centered crystal (FCC) structure with a lattice constant of 0.408nm, while LiF has a face-centered crystal structure with a lattice constant of 0.407 nm. Because the lattice constant of silver approximately matches that of LiF, silver acts as a highly effective nucleating agent for LiF. The multiplicity of these nucleation sites is extremely large and the amount of nucleation is so great that the LiF crystals do not grow to a size that can significantly scatter light, thus making the exposed areas transparent. In some embodiments, the crystallites formed in this exposed region are smaller than the visible wavelength (400nm to 750 nm). In some embodiments, the crystallite size formed in the exposed regions is less than 100 nm.

In those regions of the negative photosensitive lithium zinc aluminosilicate glass that were not exposed to such radiation (also referred to herein as "unexposed"), silver metal is not nucleated. Thus, crystals having multiple ceramic phases may grow to be much smaller in those regions of the glass that are not exposed to UV radiation, in some embodiments causing such regions to appear milky, i.e., opaque or at least translucent. In some embodiments, the crystallites formed in this unexposed region are at least as large as the visible wavelength (400nm to 750 nm). In some embodiments, the crystallite size formed in the unexposed regions is greater than 1 μm. When heated at a temperature of at least about 500 degrees celsius, a lithium-based glass-ceramic comprising a crystalline ceramic phase and residual glass forms in those regions of the glass not exposed to such radiation.

Depending on the heat treatment temperature, the crystalline ceramic phase in the regions of the precursor glass not exposed to UV radiation comprises lithium aluminosilicate (LAS, or lithionite) and lithium fluoride (LiF, or lithionite) which has a β -quartz crystal structure. The lithium aluminosilicate phase can be described as a "packed beta quartz" phase, in which LiAl is present₂O₃SiO occupying the crystal structure₂A site. In some embodiments, lithium aluminosilicate is the predominant crystalline phase; that is, lithium aluminosilicate comprises a majority of the crystalline phases present in the ceramic. The ceramic phase may further comprise LiF. In some embodiments, the lithium aluminosilicate phase comprises at least about 50 volume percent of the glass-ceramic. Lithium zinc aluminosilicate glass is clear and transparent when manufactured, but in some embodiments, when the lithium zinc aluminosilicate glass is not exposed to UV radiation in the range of 248-360nm and thermally treated (ceramming), it becomes proteolitized upon reheating to a temperature of at least about 540 degrees celsius.

At temperatures below about 540 degrees celsius, LiF is the only crystalline phase, while LiF and lithium aluminosilicate phases crystallize at higher temperatures. Silver metal nucleates LiF, and silver metal or LiF nucleates the lithium aluminosilicate phase. However, the unexposed areas lack silver precipitates, and LiF is presumed to be the nucleating phase for LAS in such areas.

The negative photosensitive glass and glass-ceramic described above also contain fluorine. Fluorine not only provides photosensitivity, but also ensures extensive crystalline phase nucleation in the unexposed areas of the precursor glass. In the absence of fluorine, the unexposed areas appear to crystallize in an uncontrolled manner, resulting in cracking and shattering of the material at temperatures of 550 degrees celsius or higher.

Upon exposure to electromagnetic radiation having a wavelength in the range of about 248nm to about 360nm, and subsequent heating at 500 degrees celsius or more (or in some embodiments at 550 degrees celsius or more) for a period ranging from about 0.5 hours to about 8 hours, about 1 hour to about 7 hours, about 1 hour to about 6 hours, about 0.5 hours to about 7 hours, about 0.5 hours to about 6 hours, about 2 hours to about 6 hours, or about 1 hour to about 5 hours, the negative photosensitive lithium aluminosilicate zinc glass is substantially free of crystalline materials of sufficient size (less than 10nm) that such materials can be detected by X-ray powder diffraction techniques, which are known in the art and are routinely used to determine crystal size.

In some embodiments, a negative photosensitive lithium zinc aluminosilicate glass comprises: from about 60 to about 80 weight percent SiO₂(i.e., 60 wt% SiO. ltoreq. SiO₂Less than or equal to 80 wt%); from about 3 to about 12 weight percent Al₂O₃(i.e., 3 wt.% or less of Al₂O₃Less than or equal to 12 wt%); from about 2 wt% to about 10 wt% Li₂O (i.e., 2 wt.% or less Li)₂O is less than or equal to 10 weight percent); from 0 to about 5 weight percent K₂O (i.e., K is not more than 0 wt%)₂O is less than or equal to 5 wt%); from greater than 0% to about 10% by weight F^-(i.e., 0% by weight)<F^-Less than or equal to 10 wt%); from greater than 0 wt.% to about 2 wt.% CeO₂(i.e., 0% by weight)<CeO₂Less than or equal to 2 wt%); from greater than 0% to about 2% by weight Ag (i.e., 0% by weight)<Ag less than or equal to 2 wt%); and from greater than 0% to about 10% by weight ZnO (i.e., 0% by weight)<ZnO is less than or equal to 10 wt%).

In some embodiments, a negative photosensitive lithium zinc aluminosilicate glass comprises: from about 66 wt% to about 76 wt% SiO₂(i.e., 66 wt% SiO. ltoreq. SiO₂Less than or equal to 76 wt%); from about 5 wt.% to about 9 wt.% Al₂O₃(i.e., 5 wt.% or more and less Al)₂O₃Less than or equal to 9 wt%); from about 5 wt% to about 8 wt% Li₂O (i.e., 5 wt% or more Li)₂O is less than or equal to 8 wt%); from greater than 0% to about 1% by weight of K₂O (i.e., 0% by weight)<K₂O is less than or equal to 1 wt%); from greater than 0% to about 6% by weight F^-(i.e., 0% by weight)<F^-Less than or equal to 6 wt%); from greater than 0 wt.% to about 0.1 wt.% CeO₂(i.e., 0% by weight)<CeO₂Less than or equal to 0.1 wt%); from greater than 0 wt% to about 0.05 wt% Ag (i.e., 0 wt%)<Ag less than or equal to 0.05 wt%); and from aboutFrom 6 wt% to about 8 wt% ZnO (i.e., 6 wt% ZnO. ltoreq.8 wt%).

In some embodiments, the negative photosensitive lithium aluminosilicate glass can comprise from about 6 wt.% to about 8 wt.% Li₂O (i.e., 6 wt% or less Li)₂O.ltoreq.8 wt%). In some embodiments, the photosensitive lithium aluminosilicate glass can comprise from about 0.5 wt.% to about 1 wt.% K₂O (i.e., K is not more than 0.5 wt%)₂O.ltoreq.1% by weight). In some embodiments, the photosensitive lithium zinc aluminosilicate glass may comprise CeO in an amount from about 0.03 wt% to about 0.09 wt%₂(i.e., 0.03 wt.% or more of CeO)₂0.09 wt.%). In some embodiments, the photosensitive lithium zinc aluminosilicate glass can comprise from greater than 0% to about 0.03% by weight Ag (i.e., 0% by weight%<Ag is less than or equal to 0.03 wt%). In some embodiments, the photosensitive lithium aluminosilicate glass can comprise from about 2 wt.% to about 4 wt.% F^-(i.e., 2 wt.% F. ltoreq. F^-4% by weight) or from about 2% to about 3.5% by weight of F^-(i.e., 2 wt.% F. ltoreq. F^-3.5 wt.%). In some embodiments, the photosensitive lithium zinc aluminosilicate glass can comprise up to about 1.5 wt.% Br^-(i.e., 0 wt.% Br or more^-4 wt.%), or from about 0.3 wt.% to about 1.5 wt.% Br^-(i.e., 0.3 wt.% Br. ltoreq.^-≦ 1.5 wt%), or from about 0.3 wt% to about 1.3 wt% Br^-(i.e., 0.3 wt.% Br. ltoreq.^-1.3 wt.%). In some embodiments, the glass is free of bromine.

In some embodiments, the negative photosensitive lithium aluminosilicate glass may comprise up to about 0.5, 0.4, 0.3, 0.2, or 0.1 wt.% Na₂O (i.e., Na is not less than 0 wt%)₂O.ltoreq.0.5 wt.%), and in some embodiments, Na is absent₂And O. In some embodiments, the photosensitive lithium aluminosilicate glass is free of MgO, P₂O₅、TiO₂And ZrO₂At least one of (a). Non-limiting examples of such negative photosensitive lithium zinc aluminosilicate glasses are listed in table 1. Exposure to ultraviolet radiation followed by exposure to 500 degrees celsius or more (or in some embodiments 550 degrees celsius or more)Above) such that the exposed area is clear and the surrounding unexposed area is hazy or even proteoperized at the temperature in some embodiments.

Table 1, composition of an example negative photosensitive lithium aluminosilicate zinc glass.

In other embodiments, the lithium zinc aluminosilicate glass is positively photosensitive; that is, regions of the material that were exposed to ultraviolet radiation having a wavelength in the range of about 248nm to about 360nm and then heat treated at the first and second temperatures, respectively, become proteolitized or translucent, while the unexposed remainder of the material remains clear after undergoing such heat treatment. In some embodiments, a positive photosensitive lithium zinc aluminosilicate glass may be obtained by changing the composition of a negative photosensitive glass ceramic or precursor glass (as described above) and subjecting the precursor glass to additional thermal treatments.

In some embodiments, a positive photosensitive lithium zinc aluminosilicate glass comprises: from about 65 to about 80 weight percent SiO₂(SiO 65 wt% or less)₂Less than or equal to 80 wt%); up to about 1 wt.% K₂O (0 wt% or less and K)₂O is less than or equal to 1 wt%); from about 3% to about 12% by weight ZnO (3% ZnO. ltoreq.12% by weight); up to about 10 wt% Br^-(0 wt% Br not more than 0)^-Less than or equal to 10 wt%); from about 5 wt.% to about 16 wt.% Al₂O₃(5% by weight or more of Al₂O₃Less than or equal to 16 wt%); from greater than 0 wt.% to about 2 wt.% CeO₂(0% by weight)<CeO₂Less than or equal to 2 wt%); from greater than 0% to about 2% by weight Ag (0% by weight<Ag less than or equal to 2 wt%); from about 2 wt% to about 14 wt% Li₂O (Li not more than 2 wt%)₂O is less than or equal to 14 weight percent); toAbout 1 wt% more Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 1 wt%); from about 0 wt.% to about 5 wt.% F^-(0 wt% F. ltoreq. F^-Less than or equal to 5 wt%); and up to about 8 wt% ZrO₂(0 wt% or less ZrO)₂Less than or equal to 8 wt%).

In some embodiments, a positive photosensitive lithium zinc aluminosilicate glass comprises: from about 68% to about 78% by weight SiO₂(68 wt.% SiO ≦₂Less than or equal to 78 wt%); up to about 1 wt.% K₂O (0 wt% or less and K)₂O is less than or equal to 1 wt%); from about 5% to about 10% by weight ZnO (5% to 10% by weight ZnO); up to about 10 wt% Br^-(0 wt% Br not more than 0)^-Less than or equal to 10 wt%); from about 5 wt.% to about 14 wt.% Al₂O₃(5% by weight or more of Al₂O₃14 wt% or less); from about 0.01 wt.% to about 0.07 wt.% CeO₂(0.01 wt% or more CeO)₂Less than or equal to 0.07 wt%); from about 0.01 wt% to about 0.05 wt% Ag (0.01 wt% Ag ≦ 0.05 wt%); from about 5 wt% to about 10 wt% Li₂O (Li not more than 5 wt%)₂O is less than or equal to 10 weight percent); up to about 1% by weight Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 1 wt%); from about 0 wt.% to about 3 wt.% F^-(0 wt% F. ltoreq. F^-Less than or equal to 3 wt%); and up to about 5 wt% ZrO₂(0 wt% or less ZrO)₂Less than or equal to 5 wt%).

In some embodiments, the positive photosensitive lithium zinc aluminosilicate precursor glass can be prepared by adding ZrO to a negative photosensitive lithium zinc aluminosilicate composition₂And is produced. Non-limiting examples of these glasses are listed in table 2 below. Example 16 in table 2 is an exemplary composition of a negative photovoltaic glass-ceramic and glass. In these embodiments, the positive photosensitive lithium zinc aluminosilicate glass comprises: from about 72 wt.% to about 76 wt.% SiO₂(72 wt% SiO. ltoreq₂Less than or equal to 76 wt%); from about 0.5% to about 1% by weight of K₂O (K is more than or equal to 0.5 weight percent₂O is less than or equal to 1 wt%); from about 5% to about 7% by weight ZnO (5% to 7% by weight ZnO); from about 0.5 wt.% to about 0.8 wt.% of% Br^-(0.5 wt% Br. or less^-Less than or equal to 0.8 wt%); from about 6 to about 8 weight percent Al₂O₃(6 wt% or less Al₂O₃Less than or equal to 8 wt%); from about 0.01 wt.% to about 0.04 wt.% CeO₂(0.01 wt% or more CeO)₂Less than or equal to 0.04 wt%); from about 0.03 wt% to about 0.05 wt% Ag (0.03 wt% Ag ≦ 0.05 wt%); from about 6 wt% to about 8 wt% Li₂O (Li not more than 6 wt%)₂O is less than or equal to 8 wt%); up to about 0.05 wt.% Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 0.05 weight percent); from about 2 to about 3 weight percent F^-(2 wt% F. ltoreq. F^-Less than or equal to 3 wt%); and from about 0.5 wt.% to about 5 wt.% ZrO₂(0.5 wt% or less ZrO)₂Less than or equal to 5 wt%).

FIG. 1 is a photograph of a specimen in which ZrO₂Added to a negative photosensitive lithium-zinc aluminosilicate precursor glass composition. The resulting glass is positively photosensitive, with a proteolitic ceramic phase present in those portions of the sample exposed to ultraviolet radiation and a lithium zinc aluminosilicate glass phase present in those portions of the sample not exposed to ultraviolet radiation. Samples A and B each had composition 19 (containing 2.92 wt% ZrO)₂) And samples C, D, and E each had composition 20 (containing 3.85 wt% ZrO)₂) The above are listed in table 2. The heat treatment times and temperatures used to form the lithium-based glass-ceramics of examples 19 and 20 are listed in table 2A. In FIG. 1, the exposed portion 110 of samples A-E is proteolitized, while the unexposed portion 120 remains clear. X-Ray diffraction (XRD) analysis of the proteoliposomic material indicated the presence of a lithionite lithium aluminosilicate phase. Fig. 2 is an X-ray diffraction pattern obtained for a proteopeptical portion of a sample having composition 18, the proteopeptical portion being exposed to ultraviolet radiation, subsequently heat treated at 575 degrees celsius for two hours, cooled to room temperature, and subsequently heat treated again at 575 degrees celsius for two hours. X-ray diffraction patterns showed that the major phase had packed beta quartz lithium aluminosilicate (dilithite Li)_xAl_xSi_3-xO₈) A crystal structure.

TABLE 2, front viewComposition of photosensitive lithium zinc aluminosilicate precursor glass, wherein ZrO is added to negative photosensitive lithium zinc aluminosilicate glass composition₂。

Table 2A, heat treatment time and temperature for the glass ceramic samples shown in fig. 1.

FIG. 1 shows a schematic view of a	Examples/compositions	First heat treatment	Second heat treatment
				A	20	At 550 ℃ for 2 hours	650 deg.C for 2 hours
B	20	At 550 ℃ for 2 hours	2 hours at 600 degrees centigrade
				C	19	2 small at 675 deg.CTime of flight	675 ℃ for 2 hours
D	19	675 ℃ for 2 hours	675 ℃ for 2 hours
				E	19	650 deg.C for 2 hours	650 deg.C for 2 hours

In other embodiments, the positive photosensitive lithium zinc aluminosilicate precursor glass is prepared by reaction of a negative photosensitive lithium aluminosilicate composition with respect to SiO₂The content is increased to increase the alumina content. In these embodiments, the positive photosensitive precursor glass comprises: from about 68% to about 76% by weight SiO₂(68 wt.% SiO ≦₂Less than or equal to 76 wt%); from about 0.5% to about 1% by weight of K₂O (K is more than or equal to 0.5 weight percent₂O is less than or equal to 1 wt%); from about 5% to about 8% by weight ZnO (5% by weight ZnO. ltoreq.8% by weight); from about 0.5 wt.% to about 1.0 wt.% Br^-(0.5 wt% Br. or less^-Less than or equal to 1.0 wt%); from about 7 wt.% to about 14 wt.% Al₂O₃(7 wt% or less Al₂O₃Less than or equal to 12 wt%); from about 0.01 wt.% to about 0.07 wt.% CeO₂(0.01 wt% or more CeO)₂Less than or equal to 0.07 wt%); from about 0.03 wt% to about 0.05 wt% Ag (0.03 wt% Ag ≦ 0.05 wt%); from about 7 to about 9 weight percent Li₂O (Li not more than 7 wt%)₂O is less than or equal to 9 wt%); up to about 0.05 wt.% Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 0.05 weight percent); and from about 2 to about 3 weight percent F^-(2 wt% F. ltoreq. F^-3% by weight or less). These glassesAnd non-limiting examples of glass-ceramics are listed in table 3 below. The alumina content in examples 21 and 22 was increased by 2 wt% and 4 wt%, respectively, relative to the composition of reference example 16 listed in table 1. Example 21 was first heat treated at 575 degrees celsius for two hours and then cooled to room temperature (about 25 degrees celsius) and then heat treated again at 575 degrees celsius for two hours, while example 22 was first heat treated at 550 degrees celsius for two hours and then cooled to room temperature and then heat treated again at 575 degrees celsius for two hours. Fig. 3 is a photograph of samples of examples 21 (F in fig. 3) and 22 (G in fig. 3) after irradiation and heat treatment. Both samples had a proteolization region 110 where exposed to ultraviolet radiation and 112 and 114 in sample G. The X-ray diffraction pattern obtained for example 22/sample G indicated that the predominant phase in the proteopeptical region had "packed beta quartz" lithium aluminosilicate (lithionite) Li_xAl_xSi_3-xO₈A crystal structure.

TABLE 3 Positive photosensitive lithium aluminosilicate precursor glass compositions with alumina content relative to SiO₂The content increases.

Examples of the invention	21	22	23	24	25	26
								By weight%	By weight%	By weight%	By weight%	By weight%	By weight%
SiO2	73.89	72.14	73.80	71.98	70.11	68.31
							K2O	0.77	0.76	0.78	0.81	0.87	0.92
ZnO	5.99	5.94	6.56	7.02	7.46	7.93
							Br-	0.71	0.70	0.72	0.76	0.82	0.87
Al2O3	9.14	11.04	7.85	8.41	9.02	9.51
							CeO2	0.03	0.03	0.03	0.03	0.06	0.06
Ag	0.04	0.04	0.04	0.04	0.04	0.04
							Li2O	7.17	7.11	7.77	8.32	8.84	9.39
Na2O	0.03	0.03	0.03	0.03	0.03	0.03
							F-	2.23	2.21	2.42	2.59	2.75	2.93
ZrO2	0.00	0.00

While ZnO is a component in negative photosensitive glass-ceramics and precursor glasses, positive photosensitive glass-ceramics and precursor glasses can be obtained by increasing the ZnO concentration relative to the alumina and silica content in the negative photosensitive lithium aluminosilicate composition. In such embodiments, the positive photosensitive glass precursor glass comprises: from about 68 to about 77 wt% SiO₂(68 wt.% SiO ≦₂Less than or equal to 77 wt%); from about 0.5% to about 1% by weight of K₂O (K is more than or equal to 0.5 weight percent₂O is less than or equal to 1 wt%); from about 6From about 10% by weight ZnO (6% by weight ZnO. ltoreq.10% by weight); from about 0.5 wt.% to about 1.0 wt.% Br^-(0.5 wt% Br. or less^-Less than or equal to 1 wt%); from about 7 wt.% to about 10 wt.% Al₂O₃(7 wt% or less Al₂O₃Less than or equal to 10 wt%); from about 0.02 wt.% to about 0.05 wt.% CeO₂(0.02 wt% or more CeO)₂Less than or equal to 0.05 wt%); from about 0.02 wt% to about 0.05 wt% Ag (0.03 wt% Ag ≦ 0.05 wt%); from about 7 to about 10 weight percent Li₂O (Li not more than 7 wt%)₂O is less than or equal to 10 weight percent); up to about 0.05 wt.% Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 0.05 weight percent); from about 1% to about 3% by weight of F^-(1 wt% F. ltoreq. F^-3% by weight) and up to about 4% by weight ZrO₂(0 wt% or less ZrO)₂4% by weight or less). Non-limiting exemplary compositions of these positive photosensitive lithium zinc aluminosilicate glasses are listed in table 4 below. In some embodiments, the glass-ceramic may be obtained by: a positive photosensitive precursor glass is first exposed to ultraviolet light, followed by a first heat treatment at about 575 degrees celsius for two hours, followed by cooling the precursor glass to room temperature (about 25 degrees celsius) and then heating the precursor glass at about 575 degrees celsius for two hours to form a glass-ceramic. Fig. 4 is a photograph of samples of examples 28 (H in fig. 4) and 30 (I in fig. 4) after irradiation and heat treatment. The sample has a proteolization region 110 where the material is exposed to ultraviolet radiation, 114 in sample H, and 112 in sample I. The X-ray diffraction pattern obtained for example 30/sample I (fig. 4) indicates that the predominant phase in the proteopeptical region has "packed beta quartz" lithium aluminosilicate (dilithite) Li_xAl_xSi_3-xO₈A crystal structure.

TABLE 4 Positive photosensitive lithium aluminosilicate zinc precursor glass compositions with ZnO concentrations relative to alumina and SiO₂The content increases.

In other embodiments, the positive photosensitive lithium zinc aluminosilicate precursor glass may be obtained by substituting bromine for fluorine. In such embodiments, the precursor glass may include up to about 10 wt.%, or in some embodiments, up to about 1 wt.% Br. In such embodiments, the positive photosensitive lithium zinc aluminosilicate precursor glass may comprise: from about 70 wt.% to about 78 wt.% SiO₂(70 wt% SiO. ltoreq. SiO₂Less than or equal to 78 wt%); from about 0.5% to about 1% by weight of K₂O (K is more than or equal to 0.5 weight percent₂O is less than or equal to 1 wt%); from about 5% to about 7% by weight ZnO (5% to 7% by weight ZnO); from about 0 wt.% to about 10 wt.% Br^-(0.5 wt% Br. or less^-Less than or equal to 10 wt%); from about 6 to about 8 weight percent Al₂O₃(6 wt% or less Al₂O₃Less than or equal to 8 wt%); from about 0.02 wt.% to about 0.05 wt.% CeO₂(0.02 wt% or more CeO)₂Less than or equal to 0.05 wt%); from about 0.02 wt% to about 0.05 wt% Ag (0.02 wt% Ag 0.05 wt%); from about 6 to about 8 weight percent Li₂O (Li not more than 6 wt%)₂O is less than or equal to 8 wt%); up to about 1% by weight Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 1 wt%); and from 0 wt% to about 3 wt% of F^-(0 wt% F. ltoreq. F^-3% by weight or less). Non-limiting examples of these glasses and glass-ceramics are listed in table 5 below. The X-ray diffraction pattern obtained for the sample of the composition listed in example 34 indicates that the predominant phase in the proteopeptization region has "packed beta quartz" lithium aluminosilicate (dilithite) Li_xAl_xSi_3-xO₈A crystal structure. Although these samples were heat treated at different temperatures, no discernible difference in X-ray diffraction data was observed.

Table 5, positive photosensitive lithium zinc aluminosilicate precursor glass compositions in which bromine is substituted for fluorine.

In another aspect, a composite glass article is provided that includes a lithium-based glass-ceramic and a photosensitive lithium zinc aluminosilicate glass. The composite glass article includes a first region and a second region. The first region includes a lithium-based glass-ceramic including a ceramic phase and a residual glass phase. The ceramic phase comprises a Lithium Aluminosilicate (LAS) phase having a lithium aluminosilicate packed beta quartz structure, such as described above. In some embodiments, the lithium-based glass-ceramic is Na-free₂O、MgO、P₂O₅、TiO₂、ZrO₂Or bromine. In some embodiments, the lithium aluminosilicate phase comprises at least about 50 volume percent of the glass-ceramic region.

The second region comprises lithium zinc aluminosilicate glass that is photosensitive to ultraviolet radiation having wavelengths in the range of about 248nm to about 360nm, such as those wavelengths described hereinabove. The lithium zinc aluminosilicate glass includes at least one sensitizer and at least one nucleating agent. In some embodiments, the at least one sensitizer may include, but is not limited to, at least one of silver or cerium. The at least one nucleating agent may include, but is not limited to, silver and/or at least one halogen or halide. In some embodiments, the at least one nucleating agent comprises at least one of fluorine, chlorine or bromine. In certain embodiments, the at least one nucleating agent comprises fluorine or bromine.

In some embodiments, the first region is opaque or translucent. In some embodiments, the lithium zinc aluminosilicate glass is transparent.

In some embodiments, the lithium zinc aluminosilicate glass is negatively photosensitive with respect to ultraviolet radiation; that is, the regions of the glass that are exposed to ultraviolet radiation and subsequently heat treated or cerammed remain transparent, while the remainder of the material that is not exposed to or shielded from such radiation and subsequently heat treated becomes proteolitized or cerammed upon heat treatment. In those embodiments in which the second region comprises a negative photosensitive lithium aluminosilicate zinc glass, the first region comprising the lithium-based glass-ceramic is not exposed (i.e., "unexposed") to ultraviolet radiation.

In some embodiments, a negative photosensitive lithium zinc aluminosilicate glass comprises: from about 66 wt% to about 76 wt% SiO₂(i.e., 66 wt% SiO. ltoreq. SiO₂Less than or equal to 76 wt%); from about 5 wt.% to about 9 wt.% Al₂O₃(i.e., 5 wt.% or more and less Al)₂O₃Less than or equal to 9 wt%); from about 5 wt% to about 8 wt% Li₂O (i.e., 5 wt% or more Li)₂O is less than or equal to 8 wt%); from greater than 0% to about 1% by weight of K₂O (i.e., 0% by weight)<K₂O is less than or equal to 1 wt%); from greater than 0% to about 6% by weight F^-(i.e., 0% by weight)<F^-Less than or equal to 6 wt%); from greater than 0 wt.% to about 0.1 wt.% CeO₂(i.e., 0% by weight)<CeO₂Less than or equal to 0.1 wt%); from greater than 0 wt% to about 0.05 wt% Ag (i.e., 0 wt%)<Ag less than or equal to 0.05 wt%); and from about 6 wt% to about 8 wt% ZnO (i.e., 6 wt% ZnO. ltoreq. 8 wt%).

In other embodiments, the second region comprises a positive photosensitive lithium zinc aluminosilicate glass; that is, the regions of the glass exposed to ultraviolet radiation having a wavelength in the range of about 248nm to about 360nm become proteolitized or translucent upon subsequent heat treatment at the first and second temperatures, respectively, while the unexposed remainder of the material remains clear after undergoing such heat treatment. These positive photosensitive glasses have been previously described above and comprise: from about 68% to about 78% by weight SiO₂(68 wt.% SiO ≦₂Less than or equal to 78 wt%); up to about 1 wt.% K₂O (0 wt% or less and K)₂O is less than or equal to 1 wt%); from about 5% to about 10% by weight ZnO (4% by weight ZnO. ltoreq.8% by weight); up to about 10 wt% Br^-(0 wt% Br not more than 0)^-Less than or equal to 10 wt%); from about 5 wt.% to about 14 wt.% Al₂O₃(5% by weight or more of Al₂O₃Less than or equal to 12 wt%); from about 0.01 wt.% to about 0.07 wt.% CeO₂(0.01 wt% or more CeO)₂Less than or equal to 0.07 wt%); from about 0.01 wt% to about 0.05 wt% Ag (0.01 wt% Ag ≦ 0.05 wt%); from about 5 wt% to about 10 wt% Li₂O (Li not more than 5 wt%)₂O is less than or equal to 10 weight percent); up to about 1 wt.% Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 1 wt%); from about 0 wt.% to about 3 wt.% F^-(0 wt% F. ltoreq. F^-Less than or equal to 3 wt%); and up to about 5 wt% ZrO₂(0 wt% or less ZrO)₂Less than or equal to 5 wt%).

In some embodiments, a positive photosensitive lithium zinc aluminosilicate glass comprises: from about 72 wt.% to about 76 wt.% SiO₂(72 wt% SiO. ltoreq₂Less than or equal to 76 wt%); from about 0.5% to about 1% by weight of K₂O (K is more than or equal to 0.5 weight percent₂O is less than or equal to 1 wt%); from about 5% to about 7% by weight ZnO (5% to 7% by weight ZnO); from about 0.5 wt.% to about 0.8 wt.% Br^-(0.5 wt% Br. or less^-Less than or equal to 0.8 wt%); from about 6 to about 8 weight percent Al₂O₃(6 wt% or less Al₂O₃Less than or equal to 8 wt%); from about 0.01 wt.% to about 0.04 wt.% CeO₂(0.01 wt% or more CeO)₂Less than or equal to 0.04 wt%); from about 0.03 wt% to about 0.05 wt% Ag (0.03 wt% Ag ≦ 0.05 wt%); from about 6 to about 8 weight percent Li₂O (Li not more than 6 wt%)₂O is less than or equal to 8 wt%); up to about 0.05 wt.% Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 0.05 weight percent); from about 2 to about 3 weight percent F^-(2 wt% F. ltoreq. F^-Less than or equal to 3 wt%); and from about 0.5 wt.% to about 5 wt.% ZrO₂(0.5 wt% or less ZrO)₂Less than or equal to 5 wt%).

In some embodiments, a positive photosensitive lithium zinc aluminosilicate glass comprises: from about 68% to about 76% by weight SiO₂(68 wt.% SiO ≦₂Less than or equal to 76 wt%); from about 0.5% to about 1% by weight of K₂O (0.5 weight)％≤K₂O is less than or equal to 1 wt%); from about 5% to about 8% by weight ZnO (5% by weight ZnO. ltoreq.8% by weight); from about 0.5 wt.% to about 1.0 wt.% Br^-(0.5 wt% Br. or less^-Less than or equal to 1.0 wt%); from about 7 wt.% to about 14 wt.% Al₂O₃(7 wt% or less Al₂O₃Less than or equal to 12 wt%); from about 0.01 wt.% to about 0.07 wt.% CeO₂(0.01 wt% or more CeO)₂Less than or equal to 0.07 wt%); from about 0.03 wt% to about 0.05 wt% Ag (0.03 wt% Ag ≦ 0.05 wt%); from about 7 to about 9 weight percent Li₂O (Li not more than 7 wt%)₂O is less than or equal to 9 wt%); up to about 0.05 wt.% Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 0.05 weight percent); and from about 2 to about 3 weight percent F^-(2 wt% F. ltoreq. F^-3% by weight or less).

In some embodiments, a positive photosensitive lithium zinc aluminosilicate glass comprises: from about 68 to about 77 wt% SiO₂(68 wt.% SiO ≦₂Less than or equal to 77 wt%); from about 0.5% to about 1% by weight of K₂O (K is more than or equal to 0.5 weight percent₂O is less than or equal to 1 wt%); from about 6% to about 10% by weight ZnO (6% by weight ZnO. ltoreq.10% by weight); from about 0.5 wt.% to about 1.0 wt.% Br^-(0.5 wt% Br. or less^-Less than or equal to 1 wt%); from about 7 wt.% to about 10 wt.% Al₂O₃(7 wt% or less Al₂O₃Less than or equal to 10 wt%); from about 0.02 wt.% to about 0.05 wt.% CeO₂(0.02 wt% or more CeO)₂Less than or equal to 0.05 wt%); from about 0.02 wt% to about 0.05 wt% Ag (0.03 wt% Ag ≦ 0.05 wt%); from about 7 to about 10 weight percent Li₂O (Li not more than 7 wt%)₂O is less than or equal to 10 weight percent); up to about 0.05 wt.% Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 0.05 weight percent); from about 1% to about 3% by weight of F^-(1 wt% F. ltoreq. F^-3% by weight) and up to about 4% by weight ZrO₂(0 wt% or less ZrO)₂4% by weight or less).

In some embodiments, the positive photosensitive lithium aluminosilicate zinc glass packageComprises the following components: from about 70 wt.% to about 78 wt.% SiO₂(70 wt% SiO. ltoreq. SiO₂Less than or equal to 78 wt%); from about 0.5% to about 1% by weight of K₂O (K is more than or equal to 0.5 weight percent₂O is less than or equal to 1 wt%); from about 5% to about 7% by weight ZnO (5% to 7% by weight ZnO); from about 0 wt.% to about 10 wt.% Br^-(0.5 wt% Br. or less^-Less than or equal to 10 wt%); from about 6 to about 8 weight percent Al₂O₃(6 wt% or less Al₂O₃Less than or equal to 8 wt%); from about 0.02 wt.% to about 0.05 wt.% CeO₂(0.02 wt% or more CeO)₂Less than or equal to 0.05 wt%); from about 0.02 wt% to about 0.05 wt% Ag (0.02 wt% Ag 0.05 wt%); from about 6 to about 8 weight percent Li₂O (Li not more than 6 wt%)₂O is less than or equal to 8 wt%); up to about 1% by weight Na₂O (Na is more than or equal to 0 weight percent₂O is less than or equal to 1 wt%); and from 0 wt% to about 3 wt% of F^-(0 wt% F. ltoreq. F^-3% by weight or less).

In some embodiments, the first region (lithium-based glass-ceramic) and the second region (lithium-zinc-aluminosilicate glass) of the composite glass article described herein may be randomly dispersed throughout the composite glass article. In other embodiments, the first region and the second region are spatially separated from each other.

In some embodiments, the first region (lithium-based glass-ceramic) and the second region (lithium-zinc-aluminosilicate glass) of the composite glass articles described herein can be arranged in an array. In some embodiments, the array may be a regularly repeating pattern, which may be short-range (i.e., having/extending to a dimension of up to about 1mm or less) or long-range (i.e., having/extending to a dimension of greater than 1 mm). Such an array may be formed by selectively irradiating portions of the precursor glass with UV light in a predetermined pattern, or by shielding a portion of the precursor glass from UV light.

In some embodiments, the lithium-based glass-ceramic has a thermal expansion Δ L measured between room temperature and a second temperature T₁/L₁And the lithium zinc aluminosilicate glass has a thermal expansion Delta L₂/L₂WhereinT is more than or equal to 25 ℃ and less than or equal to 300 ℃, and Delta L_iSize L of lithium-based glass-ceramic and lithium-zinc aluminosilicate glass_iA change in the measured temperature range. At the boundary between the glass and ceramic phases, this difference in thermal expansion places the lithium zinc aluminosilicate glass in tension and the lithium-based glass-ceramic in compression, thereby increasing the mechanical strength of the composite glass article.

The thermal expansion of the lithium-based glass ceramic and the lithium zinc aluminosilicate glass of the composite glass article is shown as a function of temperature in fig. 5A and 5B, respectively. As shown in fig. 5A and 5B, the lithium-based glass-ceramic experienced a 0.6% volume reduction with cooling from the thermal development temperature of 600 degrees celsius, while the lithium zinc aluminosilicate glass experienced a 0.3% volume reduction after cooling from the thermal development temperature. The lithium-based glass ceramic undergoes a volume reduction of more than 50% relative to the lithium-zinc aluminosilicate glass, which creates an accumulated compressive stress in the lithium-based glass ceramic at the glass-ceramic/glass interface boundary and an accumulated tensile stress in the lithium-zinc aluminosilicate glass. The compressive and tensile stress properties generated under these conditions provide stress regions that are capable of deflecting a propagating crack.

The induced stress between the lithium-based glass-ceramic and the lithium zinc aluminosilicate glass can be observed in the resulting optical birefringence and on a microscopic scale. Fig. 6A and 6B are micrographs of a composite glass article under unpolarized light and under polarized light, respectively. Composite glass article 600 includes lithium-based glass-ceramic 620 and lithium zinc aluminosilicate glass 610. The stress 614 at the interface between the lithium-based glass-ceramic 620 and the lithium zinc aluminosilicate glass 610 is visible under polarized light (fig. 6B), this stress being induced by the photoelastic effect.

Fig. 7 is a photograph showing internal stresses generated by a patterned composite glass article comprising a negative photosensitive lithium zinc aluminosilicate glass and a lithium-based glass ceramic described herein. The sample was observed between crossed polarizers and the stress magnitude was observed via the photoelastic effect (i.e., stress-induced birefringence). The composite glass article includes a lithium zinc aluminosilicate glass 710 surrounded by a lithium based glass ceramic 720. The negative photosensitive lithium zinc aluminosilicate glass in composite glass article 700 has the composition of example 16 (table 2). When viewed between crossed polarizers, stress patterns 715 appear in the glass region 710 surrounded by the glass-ceramic region 720.

The patterned composite glass articles described herein can be used to resist crack propagation from the edges of such articles by introducing compressive and tensile stresses at the boundary interface of the glass ceramic and the lithium zinc aluminosilicate glass. Such an article is schematically shown in fig. 8. Composite glass article 805 includes a first region 815 comprising lithium zinc aluminosilicate glass and a second region comprising lithium-based glass ceramic 815. Both lithium zinc aluminosilicate glasses and lithium based glass ceramics are described herein. If the lithium zinc aluminosilicate glass is positively photosensitive, the central portion 810 of the precursor glass 800 is not exposed to UV radiation, while the peripheral portion 820 of the precursor glass 800 is exposed to UV radiation. After exposure to UV radiation (830 in fig. 8), the precursor lithium zinc aluminosilicate glass is heated to and held at a first temperature for a predetermined period of time and cooled to room temperature (840), then heated to and held at a second temperature for a predetermined period of time and cooled to room temperature (850) to form the lithium-based glass ceramic and composite glass article 805. The glass-ceramic is formed in the exposed peripheral portion 820, wherein at the interface between the lithium aluminosilicate zinc glass and the lithium-based glass-ceramic, a compressive stress (815 in fig. 8) is present within the lithium-based glass-ceramic, and a tensile stress is generated in the lithium aluminosilicate zinc glass. This interfacial stress resists crack propagation from the edge of the composite glass article 805.

In those examples where the lithium aluminosilicate zinc glass is negatively photosensitive, the central portion 810 of the precursor glass 800 is exposed to UV radiation while the peripheral portion 820 of the precursor glass 800 is not exposed to UV radiation. After exposure to UV radiation (830 in fig. 8), the precursor lithium zinc aluminosilicate glass is heated to and held at a first temperature for a predetermined period of time and cooled to room temperature (845) to form the lithium-based glass ceramic and composite glass article 805.

In another aspect, a method of making a composite glass article with a negative photosensitive lithium zinc aluminosilicate precursor glass (precursor glass) as described above is provided. The composite glass article comprises lithium zinc aluminosilicateGlass and lithium-based glass-ceramics. The lithium-based glass-ceramic comprises a residual glass phase and a ceramic phase, the ceramic phase comprising a packed beta-quartz lithium aluminosilicate (dilithite, or Li)_xAl_xSi_3-xO₈) The crystal structure, and in some embodiments, includes a crystalline LiF phase. In some embodiments, the lithium-based glass-ceramic may be proteolized or may be translucent.

A flow chart describing the method is shown in fig. 9. In a first step 910 of method 900, a negative photosensitive lithium zinc aluminosilicate precursor glass is provided, the negative photosensitive lithium zinc aluminosilicate precursor glass including at least one sensitizer and at least one nucleating agent. The precursor glass may be formed by means known in the art, including downdraw (melting or slot draw), updraft, float processes, casting, molding, and the like.

In a second step 920, a first region of the negative photosensitive lithium zinc aluminosilicate precursor glass is exposed to ultraviolet radiation having a wavelength in a range from about 248nm to about 360nm, while a second region of the negative photosensitive lithium zinc aluminosilicate precursor glass is not exposed to ultraviolet radiation. In some embodiments, the first region is irradiated with a UV laser, such as a 355nm pulsed laser or the like, or a continuous beam of UV light, such as a 310nm Hg arc lamp; without irradiating a second region of the precursor glass with UV radiation (i.e., without exposure to UV radiation). In other embodiments, the second region of the precursor glass may be shielded from UV radiation. Such masking may include an opaque or reflective film, such as those known in the art, applied to the second area surface. As previously described, in some embodiments, the UV radiation may have a 355nm wavelength, a 10Hz frequency, and 6.5W/cm²Flux. In some embodiments, the UV laser or beam is scanned over at least a portion of the negative photosensitive lithium zinc aluminosilicate precursor glass. For example, the precursor glass may be irradiated with UV light scanned over the material at a rate of 10mm/sec for 5 seconds. In other embodiments, the negative photosensitive lithium zinc aluminosilicate precursor glass may be continuously irradiated with UV light for a fixed period of time (e.g., about 1 minute, or a time ranging from about 5 to about 10 seconds).

The UV exposed negative photosensitive lithium zinc aluminosilicate precursor glass is then heated to form a lithium-based glass-ceramic in the second region, thereby forming a composite glass article (step 930). In some embodiments, the lithium zinc aluminosilicate precursor glass is exposed to heat at a temperature ranging from about 550 degrees celsius to about 650 degrees celsius for at least about 2 hours. In some embodiments, the crystalline lithium aluminosilicate and LiF phases (when present) in the second region not exposed to UV radiation have crystal sizes at least as large as visible wavelengths (greater than 400nm), thus scattering and being proteolitized, making the ceramic phase opaque or translucent. However, in some embodiments, the crystal size in the second region is small enough so as not to scatter or refract light slightly, thus making the ceramic phase transparent.

In yet another aspect, a method of making a composite glass article with a positive photosensitive lithium zinc aluminosilicate precursor glass (precursor glass) as described above is provided. Composite glass articles include lithium zinc aluminosilicate glasses and lithium-based glass ceramics. The lithium-based glass-ceramic comprises a residual glass phase and a ceramic phase, the ceramic phase comprising a packed beta-quartz lithium aluminosilicate (dilithite, or Li)_xAl_xSi_3-xO₈) The crystal structure, and in some embodiments, includes a crystalline LiF phase. In some embodiments, the lithium-based glass-ceramic may be proteolized or translucent.

A flow chart describing the method is shown in fig. 10. In a first step 1010 of method 1000, an ortho-photosensitive lithium zinc aluminosilicate precursor glass is provided, the ortho-photosensitive lithium zinc aluminosilicate precursor glass including at least one sensitizer and at least one nucleating agent. The precursor glass may be formed by means known in the art, including downdraw (melting or slot draw), updraft, float processes, casting, molding, and the like.

In a second step 1020, a first region of the ortho-photosensitive lithium zinc aluminosilicate precursor glass is exposed to ultraviolet radiation having a wavelength in a range from about 248nm to about 360nm, while a second region of the lithium zinc aluminosilicate glass is not exposed (i.e., is not exposed) to the ultraviolet radiation. In some embodiments, the first region is irradiated with a UV laser, such as a 355nm pulsed laser or the like, or a continuous beam of UV light, such as a 310nm Hg arc lamp; without using UV radiationA second region of the precursor glass is shot irradiated. In other embodiments, the second region of the precursor glass may be shielded from UV radiation. Such masking may include an opaque or reflective film, such as those known in the art, applied to the second area surface. As previously described, in some embodiments, the UV radiation may have a 355nm wavelength, a 10Hz frequency, and 6.5W/cm²Energy. In some embodiments, the UV laser or focused beam is scanned over at least a portion of the negative photosensitive lithium zinc aluminosilicate precursor glass. For example, the precursor glass may be irradiated with UV light scanned over the material at a rate of 10mm/sec for 5 seconds. In other embodiments, the ortho-photosensitive lithium zinc aluminosilicate precursor glass may be continuously irradiated with UV light for a fixed period of time (e.g., about 1 minute, or a time not ranging from about 5 to about 10 seconds, or in some embodiments, up to two hours).

After exposure to UV radiation, the lithium zinc aluminosilicate precursor glass is heated at a first temperature for a first predetermined period of time to reduce silver by using cerium as an optical medium (step 1030). In some embodiments, the first temperature is in a range from about 550 degrees celsius to about 700 degrees celsius and the first predetermined period of time is in a range from about 0.5 hours to about 4 hours. The precursor glass is then cooled to room temperature (approximately 25 degrees celsius) (not shown). The exposed precursor glass is then heated at a second temperature for a second predetermined period of time to form a lithium-based glass-ceramic in the first region, wherein the glass-ceramic comprises a residual glass phase and a ceramic phase comprising a packed beta quartz lithium aluminosilicate (dilithite, or Li)_xAl_xSi_{3- x}O₈) The crystal structure, and in some embodiments, the crystalline LiF phase (step 1040), is included, and a composite glass article is formed therefrom. In some embodiments, the second temperature is in a range from about 500 degrees celsius to about 700 degrees celsius, and the second predetermined period of time is in a range from about 0.5 hours to about 4 hours. Finally, the composite glass article is cooled to room temperature (approximately 25 degrees celsius) (not shown).

While typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed to be a limitation on the scope of the disclosure or the appended claims. Accordingly, various modifications, adaptations, and alternatives may occur to one skilled in the art without departing from the spirit and scope of the present disclosure or appended claims.