HIGH REFRACTIVE INDEX PHOSPHATE GLASS

Abstract

Disclosed herein are glasses that present several advantages over traditional glass compositions used in optical applications. The glasses disclosed herein have a low devitrification tendency and can be processed by melt quenching and formed into macroscopic components. The glasses have high glass thermal stability indices and are chemically durable. The glasses disclosed herein are transparent when heat treated in air or oxygen and have high refractive indices and low density, as well, making them suitable for optical applications.

Claims

1. A glass composition comprising: (a) P.sub.2O.sub.5 in an amount of 15 mol % to 40 mol %; and (b) Nb.sub.2O.sub.5 in an amount of 10 mol % to 50 mol %; and (c) TiO.sub.2 in an amount of 15 mol % to 30 mol %; and (d) alkali metal oxide (R.sub.2O) in an amount of 5 mol % to 25 mol %, the alkali metal oxide (R.sub.2O) comprising at least two of Li.sub.2O, Na.sub.2O, and K.sub.2O, the alkali metal oxide (R.sub.2O) comprising less than 20 mol % Na.sub.2O; and (e) alkaline earth metal oxide (RO) in an amount of 5 mol % to 30 mol %, the alkaline earth metal oxide (RO) comprising at least two of CaO, SrO, and BaO; and wherein the glass composition does not include ZnO and B.sub.2O.sub.3; and wherein the glass composition has a molar ratio of (R.sub.2O+RO)/P.sub.2O.sub.5 greater than or equal to 1.

2. The glass composition of claim 1, wherein the amount of P.sub.2O.sub.5 is 20 mol % to 30 mol %.

3. The glass composition of claim 1, wherein the amount of Nb.sub.2O.sub.5 is 15 mol % to 25 mol %.

4. The glass composition of claim 1, wherein the amount of TiO.sub.2 is 19 mol % to 27 mol %.

5. The glass composition of claim 1, wherein the glass composition further comprises WO.sub.3 in an amount of 1 mol % to 15 mol %.

6. The glass composition of claim 1, wherein the amount of Nb.sub.2O.sub.5 is 15 mol % to 25 mol % and the amount of TiO.sub.2 is 15 mol % to 25 mol %.

7. The glass composition of claim 1, wherein the alkaline earth metal oxide (RO) comprises BaO in the amount of 1 mol % to 25 mol % and CaO in the amount of 1 mol % to 25 mol %.

8. The glass composition of claim 1, wherein the alkali metal oxide (R.sub.2O) comprises Na.sub.2O in the amount of 1 mol % to 15 mol %, Li.sub.2O in the amount of 1 mol % to 15 mol %, and K.sub.2O in the amount of 1 mol % to 10 mol %, and the alkaline earth metal oxide (RO) comprises BaO in the amount of 1 mol % to 25 mol % and CaO in the amount of 1 mol % to 25 mol %.

9. The glass composition of claim 1, wherein the glass composition has a refractive index of at least 1.85 at 588 nm at 25° C.

10. The glass composition of claim 1, wherein the glass composition has a density of less than or equal to 3.8 g/cm.sup.3.

11. The glass composition of claim 1, wherein the glass composition has an internal liquidus temperature of 875° C. to 1,200° C.

12. A glass composition comprising: (a) P.sub.2O.sub.5 in an amount of 15 mol % to 40 mol %; and (b) Nb.sub.2O.sub.5 in an amount of 10 mol % to 50 mol %; and (c) TiO.sub.2 in an amount of 15 mol % to 30 mol %; and (d) alkali metal oxide (R.sub.2O) in an amount of 5 mol % to 25 mol %, the alkali metal oxide (R.sub.2O) comprising at least one of Li.sub.2O and K.sub.2O in an amount of at least 1 mol %; and (e) alkaline earth metal oxide (RO) in an amount of 5 mol % to 30 mol %, the alkaline earth metal oxide (RO) comprising at least two of CaO, SrO, and BaO; and wherein the glass composition does not include ZnO and B.sub.2O.sub.3; and wherein the glass composition has a molar ratio of (R.sub.2O+RO)/P.sub.2O.sub.5 greater than or equal to 1.

13. The glass composition of claim 12, wherein the amount of P.sub.2O.sub.5 is 20 mol % to 30 mol %.

14. The glass composition of claim 12, wherein the amount of Nb.sub.2O.sub.5 is 15 mol % to 25 mol %.

15. The glass composition of claim 12, wherein the amount of TiO.sub.2 is 19 mol % to 27 mol %.

16. The glass composition of claim 12, wherein the alkali metal oxide (R.sub.2O) comprises at Li.sub.2O in an amount of at least 1 mol % and K.sub.2O in an amount of at least 1 mol %.

17. The glass composition of claim 12, wherein the glass composition further comprises WO.sub.3 in an amount of 1 mol % to 15 mol %.

18. The glass composition of claim 12, wherein the amount of Nb.sub.2O.sub.5 is 15 mol % to 25 mol % and the amount of TiO.sub.2 is 15 mol % to 25 mol %.

19. The glass composition of claim 12, wherein the alkaline earth metal oxide (RO) comprises BaO in the amount of 1 mol % to 25 mol % and CaO in the amount of 1 mol % to 25 mol %.

20. The glass composition of claim 12, wherein the alkali metal oxide (R.sub.2O) comprises Na.sub.2O in the amount of 1 mol % to 15 mol %, Li.sub.2O in the amount of 1 mol % to 15 mol %, and K.sub.2O in the amount of 1 mol % to 10 mol %, and the alkaline earth metal oxide (RO) comprises BaO in the amount of 1 mol % to 25 mol % and CaO in the amount of 1 mol % to 25 mol %.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects described below:

[0006] FIGS. 1A and 1B show the transmittance of a glass composition heated at 660° C. with oxygen purge for 0.5 hour and 1 hour (FIG. 1A) and in air at 640° C. for 1 hour (FIG. 1B) compared to the same glass composition that was not heated.

[0007] FIG. 2 shows the refractive index of a glass composition that was heated at 660° C. with oxygen purge for 16 hours compared to the same glass that was not heated under oxygen.

[0008] FIGS. 3A and 3B show that glass compositions that include CeO.sub.2 have a higher refractive index and transmittance, respectively, compared to a glass composition that does not include CeO.sub.2.

DETAILED DESCRIPTION

[0009] Before the present materials, articles, and/or methods are disclosed and described, it is to be understood that the aspects described below are not limited to specific compounds, synthetic methods, or uses, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

[0010] In the specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings:

[0011] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a metal oxide” in a glass composition includes mixtures of two or more metal oxides and the like.

[0012] “Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not. For example, the glass compositions described herein may optionally contain an alkaline earth metal oxide, where the alkaline earth metal oxide may or may not be present.

[0013] As used herein, the term “about” is used to provide flexibility to a numerical range endpoint by providing that a given numerical value may be “a little above” or “a little below” the endpoint without affecting the desired result. For purposes of the present disclosure, “about” refers to a range extending from 10% below the numerical value to 10% above the numerical value. For example, if the numerical value is 10, “about 10” means between 9 and 11 inclusive of the endpoints 9 and 11.

[0014] Throughout this specification, unless the context dictates otherwise, the word “comprise,” or variations such as “comprises” or “comprising,” will be understood to imply the inclusion of a stated element, integer, step, or group of elements, integers, or steps, but not the exclusion of any other element, integer, step, or group of elements, integers, or steps.

[0015] The “refractive index” of a material is a number that describes how light propagates through that material. It is defined by the equation n=c/v, where c is the speed of light in a vacuum and v is the speed of light as it propagates through the material. In one aspect, the refractive indices of the materials disclosed herein show little variation over the measured wavelength range and, hence, are characterized by low dispersion.

[0016] As used herein, the “glass transition temperature” (T.sub.g) of a material characterizes the temperature at which the glass transition occurs in an amorphous material. At temperatures below T.sub.g, the material exists in a hard and brittle state and at temperatures above T.sub.g, the material exists in a supercooled liquid state. T.sub.g is always lower than the melting temperature of a material's crystalline state, if a crystalline state exists for the material.

[0017] As used herein, “devitrification” is the formation of crystalline structures in glass. Devitrification can result from improper cleaning of glass surfaces, during cooling of the melt from melting temperatures, from holding the glass at a high temperature for a long time (which may cause crystals to nucleate), or simply from the tendencies of the raw materials in the glass. In one aspect, simple binary titanium phosphate glasses have a high devitrification tendency. In a further aspect, devitrification can be avoided by using rapid quenching techniques such as, for example, roller quenching. In a still further aspect, the glass compositions disclosed herein have low devitrification tendencies and thus can be quenched to the glassy state using cooling rates that are substantially slower than those associated with roller quenching.

[0018] As used herein, “glass thermal stability index” refers to the temperature difference between the onset of crystallization (T.sub.x) and the glass transition (T.sub.g) (i.e., T.sub.x−T.sub.g) as measured by differential scanning calorimetry (DSC). The onset crystallization determined by DSC is the onset crystallization peak upon heating of a glass from room temperature to melting temperature at a rate of 10° C./min. Methods for determining the onset of crystallization (T.sub.x) are provided in the Examples. In one aspect, the glass compositions described herein have a high glass thermal stability index. In a further aspect, the glass compositions described herein can have a glass thermal stability index of 100° C. or greater, or 150° C. or greater, or 200° C. or greater. In other aspects, a crystalline state does not exist for the glass composition and the glass thermal stability index is a negative number corresponding to −T.sub.g.

[0019] “Dispersion” as used herein is a change in the refractive index of a material with wavelength. In one aspect, the glass compositions described herein have lower dispersion than other high refractive index glasses such as, for example, glasses containing lead or bismuth.

[0020] “Melt quenching” is a common technique for producing glasses. In melt quenching, raw materials are mixed into a batch and melted; the duration and temperature of the melt depend on the melting points of the individual components. Following melting, the glass can be cast and then annealed near T.sub.g to remove thermal stresses that may remain. Glasses that have been melt quenched can be further processed by sawing, grinding, polishing, and other techniques. In one aspect, the glass compositions disclosed herein can be processed via melt quenching. In a further aspect, the glass compositions disclosed herein can be fabricated into macroscopic pieces.

[0021] “Roller quenching” is a rapid quenching technique used in the processing of materials with poor glass forming tendencies into glasses. In roller quenching, the glass melt is poured through rollers. In one aspect, the glass compositions disclosed herein have good glass forming tendencies and do not need to be processed by roller quenching.

[0022] “Annealing” as used herein is the process of slowly cooling hot glass after the formation of an object from the glass melts as well as reheating the glass from room temperature to annealing point and keep at annealing point for certain time, and then slowly cooling back to room temperature. In one aspect, annealing can relieve internal stresses introduced during the manufacture of a glass object. In another aspect, the glasses described herein can be strongly colored when formed by conventional melting in air, but can be bleached to transparency by annealing in air or oxygen at elevated temperatures, including temperatures near T.sub.g. The “annealing temperature” or “annealing point” of glass is the temperature at which the viscosity of the glass reaches 10.sup.13.2 Poise. In one aspect, at the annealing temperature, the viscosity of the glass is still high enough that the glass can resist external deformation (and any resultant breakage) but becomes just soft enough to relax internal strains. In one aspect, the annealing points of the glasses disclosed herein can range from 450 to 750° C.

[0023] A material such as an object formed from a glass composition can change in shape, area, or volume in response to a change in temperature. The “coefficient of thermal expansion” is the degree of expansion divided by the change in temperature and can vary with temperature. Methods for determining the coefficient of thermal expansion are provided in the Examples.

[0024] References in the specification and claims to atomic percentages of a particular element in a composition or article denote the molar relationship between the element or component and any other elements or components in the composition or article for which an atomic percentage is expressed. Thus, in a composition containing 2 atomic percent of component X and 5 atomic percent of component Y, X and Y are present at a molar ratio of 2:5, and are present in such a ratio regardless of whether additional components are used in the composition.

[0025] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of any such list should be construed as a de facto equivalent of any other member of the same list based solely on its presentation in a common group, without indications to the contrary.

[0026] Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range was explicitly recited. As an example, a numerical range of “about 1” to “about 5” should be interpreted to include not only the explicitly recited values of about 1 to about 5, but also to include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3, and 4, the sub-ranges such as from 1-3, from 2-4, from 3-5, from about 1-about 3, from 1 to about 3, from about 1 to 3, etc., as well as 1, 2, 3, 4, and 5, individually. The same principle applies to ranges reciting only one numerical value as a minimum or maximum. Furthermore, such an interpretation should apply regardless of the breadth or range of the characters being described.

[0027] Disclosed are materials and components that can be used for, can be used in conjunction with, can be used in preparation for, or are products of the disclosed compositions and methods. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed, that while specific reference to each various individual combination and permutation of these compounds may not be explicitly disclosed, each is specifically contemplated and described herein. For example, if an alkali metal oxide additive is disclosed and discussed, and a number of different alkaline earth metal oxide additives are discussed, each and every combination of alkali metal oxide additive and alkaline earth metal oxide additive that is possible is specifically contemplated unless specifically indicated to the contrary. For example, if a class of alkali metal oxides A, B, and C is disclosed, as well as a class of alkaline earth metal oxide additives D, E, and F, and an example combination of A+D is disclosed, then even if each is not individually recited, each is individually and collectively contemplated. Thus, in this example, each of the combinations A+E, A+F, B+D, B+E, B+F, C+D, C+E, and C+F is specifically contemplated and should be considered from disclosure of A, B, ad C; D, E, and F; and the example combination A+D. Likewise, any subset or combination of these is also specifically contemplated and disclosed. Thus, for example, the sub-group of A+E, B+F, and C+E is specifically contemplated and should be considered from disclosure of A, B, and C; D, E, and F; and the example combination of A+D. This concept applies to all aspects of the disclosure including, but not limited to, steps in methods of making and using the disclosed compositions. Thus, if there are a variety of additional steps that can be performed with any specific embodiment or combination of embodiments of the disclosed methods, each such composition is specifically contemplated and should be considered disclosed.

[0028] The term “R.sub.2O” refers to alkali metal oxide and is used to represent the combination of all alkali metal oxides in a glass composition. Alkali metal oxides include Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O, and Cs.sub.2O. If only one alkali metal oxide is present in a composition, R.sub.2O refers to that alkali metal oxide. If two or more alkali metal oxides are present in a composition, R.sub.2O refers to all alkali metal oxides collectively. Reference to amount or concentration of R.sub.2O means the combined amount or concentration of all (one or more) alkali metal oxides expressed as mol %.

[0029] The term “RO” refers to alkaline earth metal oxide and is used to represent the combination of all alkaline earth metal oxides in a glass composition. Alkaline earth metal oxides include MgO, CaO, SrO, and BaO. If only one alkaline earth metal oxide is present in a composition, RO refers to that alkaline earth metal oxide. If two or more alkaline earth metal oxides are present in a composition, RO refers to all alkaline earth metal oxides collectively. Reference to amount or concentration of RO means the combined amount or concentration of all (one or more) alkaline earth metal oxides expressed as mol %.

[0030] Unless otherwise specified, amounts or concentrations described herein for components in a glass composition refer to mol % of components included in the glass composition produced herein.

[0031] The glass compositions described herein include phosphorous pentoxide (P.sub.2O.sub.5), niobium pentoxide (Nb.sub.2O.sub.5), one or more alkali metal oxides (R.sub.2O), one or more alkaline earth metal oxides (RO), and one or more optional glass-forming components. As will be discussed in detail below, by varying the relative amounts of each of these components the properties of the glass composition can be modified.

[0032] The glass compositions described herein contain P.sub.2O.sub.5. In one aspect, the amount of P.sub.2O.sub.5 is from about 20 mol % to about 40 mol %. In another aspect, the amount of P.sub.2O.sub.5 is about 20, 25, 30, 35, or 40 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 25 mol % to 40 mol %, 25 mol % to 35 mol %, etc.).

[0033] The glass compositions described herein contain Nb.sub.2O.sub.5. In one aspect, the amount of Nb.sub.2O.sub.5 is from about 10 mol % to about 50 mol %. In a still further aspect, the Nb.sub.2O.sub.5 is present at about 10, 15, 20, 25, 30, 35, 40, 45, or 50 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 15 mol % to 30 mol %, 20 mol % to 30 mol %, etc.). The presence of Nb.sub.2O.sub.5 in the glasses described herein contributes to an increase in refractive index of the glass materials.

[0034] The glass compositions described herein contain one or more alkali metal oxides (R.sub.2O), which includes Na.sub.2O, Li.sub.2O, K.sub.2O, or any combination thereof. In one aspect, the amount of the alkali metal oxide is from about 1 mol % to about 35 mol %. In a still further aspect, the alkali metal oxide is present at about 1, 5, 10, 15, 20, 25, 30, or 35 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 5 mol % to 15 mol %, 5 mol % to 20 mol %, etc.).

[0035] In one aspect, the alkali metal oxide is Na.sub.2O in the amount of 1 mol % to 35 mol %. In another aspect, the alkali metal oxide is Li.sub.2O in the amount of 1 mol % to 15 mol %. In another aspect, the alkali metal oxide is K.sub.2O in the amount of 1 mol % to 10 mol %. In the case when a single alkali metal oxide is present in the glass composition, the amount of alkali metal oxide is from 1 mol % to 35 mol %. In a further aspect, the alkali metal oxide is Na.sub.2O in the amount of 1 mol % to 35 mol %, Li.sub.2O in the amount of 1 mol % to 15 mol %, and K.sub.2O in the amount of 1 mol % to 10 mol %, where the sum of R.sub.2O is from about 1 mol % to about 35 mol %.

[0036] The glass compositions described herein contain one or more alkaline earth metal oxides (RO), which includes CaO, BaO, MgO, SrO, or any combination thereof. In one aspect, the amount of the alkaline earth metal oxide is from about 5 mol % to about 40 mol %. In a still further aspect, the alkali earth metal oxide is present at about 5, 10, 15, 20, 25, 30, 35, or 40 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 1 mol % to 15 mol %, 5 mol % to 20 mol %, etc.).

[0037] In one aspect, the alkaline earth metal oxide is BaO in the amount of 1 mol % to 25 mol %. In another aspect, the alkaline earth metal oxide is CaO in the amount of 1 mol % to 20 mol %. In another aspect, the alkaline earth metal oxide is MgO in the amount of 1 mol % to 15 mol %. In another aspect, the alkaline earth metal oxide is SrO in the amount of 1 mol % to 30 mol %. In the case when a single alkaline earth metal oxide is present in the glass composition, the amount of single alkaline earth metal oxide is from 5 mol % to 40 mol %. In a further aspect, the alkaline earth metal oxide is BaO in the amount of 1 mol % to 25 mol % and CaO in the amount of 1 mol % to 20 mol %, where the sum of BaO and CaO is from 1 mol % to 40 mol %. In another aspect, the alkaline earth metal oxide is BaO in the amount of 1 mol % to 25 mol %, CaO in the amount of 1 mol % to 20 mol %, and SrO in the amount of 1 mol % to 30 mol %, where the sum of BaO, CaO, and SrO is from 5 mol % to 40 mol %.

[0038] The amount of P.sub.2O.sub.5, alkali metal oxide, and alkaline earth metal oxide can be varied in order modify the properties of the glass composition. In one aspect, the molar ratio of R.sub.2O/(R.sub.2O+RO) is greater than 0.25. In another aspect, the molar ratio of R.sub.2O/(R.sub.2O+RO) is greater than 0.25, or 0.5, 0.75, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, where any value can be a lower- and upper-endpoint of a range (e.g., greater than 0.25 to 2, 0.5 to 5, etc.). Here and throughout the present description, R.sub.2O and RO can include one or more alkali metal oxides and alkaline earth metal oxides, respectively. Not wishing to be bound by theory, when R.sub.2O/(R.sub.2O+RO) is greater than 0.25 the transmittance of the glass composition improves.

[0039] In one aspect, when the glass composition includes R.sub.2O and RO, the molar ratio of (R.sub.2O+RO)/P.sub.2O.sub.5 is greater than or equal to 1. In another aspect, the molar ratio of (R.sub.2O+RO)/P.sub.2O.sub.5 is greater than 1, or 2, 3, 4, 5, 6, 7, 8, 9, or 10, where any value can be a lower- and upper-endpoint of a range (e.g., greater than 1 to 3, 2 to 5, etc.). In other aspects, when the glass composition includes R.sub.2O and RO, the molar ratio of (R.sub.2O+RO)/P.sub.2O.sub.5 is less than or equal to 1.

[0040] In one aspect, when the glass composition includes RO and not R.sub.2O, the molar ratio of RO/P.sub.2O.sub.5 is greater than or equal to 1. In another aspect, the molar ratio of RO/P.sub.2O.sub.5 is greater than 1, or 2, 3, 4, 5, 6, 7, 8, 9, or 10, where any value can be a lower- and upper-endpoint of a range (e.g., greater than 1 to 3, 2 to 5, etc.). In other aspects, when the glass composition includes RO and not R.sub.2O, the molar ratio of RO/P.sub.2O.sub.5 is less than or equal to 1.

[0041] In one aspect, when the glass composition includes R.sub.2O and not RO, the molar ratio of R.sub.2O/P.sub.2O.sub.5 is greater than or equal to 1. In another aspect, the molar ratio of R.sub.2O/P.sub.2O.sub.5 is greater than 1, or 2, 3, 4, 5, 6, 7, 8, 9, or 10, where any value can be a lower- and upper-endpoint of a range (e.g., greater than 1 to 3, 2 to 5, etc.). In other aspects, when the glass composition includes R.sub.2O and not RO, the molar ratio of R.sub.2O/P.sub.2O.sub.5 is less than or equal to 1.

[0042] In one aspect, the glass compositions described herein contain TiO.sub.2. In one aspect, the amount of TiO.sub.2 is from about 1 mol % to about 30 mol %. In a still further aspect, TiO.sub.2 is present at about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 1 mol % to 15 mol %, 5 mol % to 20 mol %, etc.).

[0043] In one aspect, the glass compositions described herein contain WO.sub.3. In one aspect, the amount of WO.sub.3 is from about 1 mol % to about 15 mol %. In a still further aspect, WO.sub.3 is present at about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 1 mol % to 5 mol %, 5 mol % to 10 mol %, 10 mol % to 15 mol %, etc.).

[0044] In one aspect, when the glass composition includes TiO.sub.2 and/or WO.sub.3, the sum of Nb.sub.2O.sub.5 with TiO.sub.2 and/or WO.sub.3 is in the amount of 20 mol % to 50 mol %. In a still further aspect, the sum of Nb.sub.2O.sub.5 with TiO.sub.2 and/or WO.sub.3 is at about 20, 25, 30, 35, 40, 45, or 50 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 20 mol % to 30 mol %, 30 mol % to 40 mol %, etc.).

[0045] In one aspect, the glass composition includes ZnO. In this aspect, the amount of ZnO is from 0.5 mol % to about 20 mol %, or is about 0.5, 1, 2, 3, 4, 5, 10, 15, or 20 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 1 mol % to 15 mol %, 5 mol % to 10 mol %, etc.). In one aspect, the sum of RO, R.sub.2O, and ZnO is in the amount of 30 mol % to 60 mol %, or is about 30, 25, 40, 45, 50, 55, or 60 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 30% to 45%, 40% to 55%, etc.).

[0046] In another aspect, the glass composition includes Al.sub.2O.sub.3. In this aspect, the amount of Al.sub.2O.sub.3 is greater than 0 mol % and less than or equal to about 5 mol %, or is about 1, 2, 3, 4, or 5 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 1 mol % to 5 mol %, 2 mol % to 4 mol %, etc.).

[0047] In another aspect, the glass composition includes SnO.sub.2. In this aspect, the amount of SnO.sub.2 is greater than 0 mol % and less than or equal to about 2 mol %, or is about 0.1, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, or 2.0 mol %, where any value can be a lower- and upper-endpoint of a range (e.g., 0.1 mol % to 2.0 mol %, 0.25 mol % to 1.75 mol %, etc.).

[0048] In one aspect, the glass compositions described herein further contain one or more metal oxides selected from the group consisting of Rb.sub.2O, Cs.sub.2O, CdO, MnO.sub.2, Y.sub.2O.sub.3, La.sub.2O.sub.3, HfO.sub.2, Ta.sub.2O.sub.5, ZrO.sub.2, Ga.sub.2O.sub.3, SiO.sub.2, GeO.sub.2, Sb.sub.2O.sub.3, Bi.sub.2O.sub.3, and combination thereof. In another aspect, the glass compositions contain one, two, three, or four metal oxides from those listed above. In certain aspects, the glass compositions described herein do not include SiO.sub.2, Al.sub.2O.sub.3, MgO, TiO.sub.2, or any combination thereof. In another aspect, the glass compositions described herein do not include B.sub.2O.sub.3.

[0049] In one aspect, a first glass composition includes

(a) P.sub.2O.sub.5 in an amount of 15 mol % to 40 mol %;
(b) Nb.sub.2O.sub.5 is in an amount of 10 mol % to 50 mol %;
(c) an alkali metal oxide (R.sub.2O) in an amount of 1 mol % to 35 mol %; and
(d) at least two alkaline earth metal oxides (RO) in a combined amount of 5 mol % to 40 mol %,
wherein the glass composition does not include ZnO and B.sub.2O.sub.3.

[0050] In one aspect, with respect to the first glass composition above, in another aspect the amount of P.sub.2O.sub.5 is from 25 mol % to 35 mol %; the amount of Nb.sub.2O.sub.5 is from 20 mol % to 35 mol %; the amount of R.sub.2O is from 10 mol % to 35 mol %, and the amount of RO is from 20 mol % to 40 mol %. In a further aspect, the first glass composition includes WO.sub.3 in the amount from about 1 mol % to about 15 mol % and/or TiO.sub.2 in the amount from about 1 mol % to about 20 mol %, wherein the sum of Nb.sub.2O.sub.5 with TiO.sub.2 and/or WO.sub.3 is in the amount of 20 mol % to 40 mol %.

[0051] In one aspect, with respect to the first glass composition above, R.sub.2O is Na.sub.2O in the amount of 1 mol % to 15 mol %, Li.sub.2O in the amount of 1 mol % to 15 mol %, and K.sub.2O is in the amount of 1 mol % to 10 mol %, BaO is in the amount of 1 mol % to 25 mol %, CaO is in the amount of 1 mol % to 25 mol %, and SrO is in the amount of 1 mol % to 25 mol %.

[0052] In one aspect, a second glass composition includes

(a) P.sub.2O.sub.5 in an amount of 15 mol % to 40 mol %;
(b) Nb.sub.2O.sub.5 is in an amount of 10 mol % to 50 mol %;
(c) at least one alkali metal oxide (R.sub.2O) in an amount of 5 mol % to 35 mol %; and
wherein the glass composition does not include ZnO, B.sub.2O.sub.3, or an alkaline earth metal oxide (RO).

[0053] In one aspect, with respect to the second glass composition above, Nb.sub.2O.sub.5 is in the amount of 30 mol % to 40 mol % and TiO.sub.2 in the amount of 5 mol % to 15 mol %, P.sub.2O.sub.5 is in an amount of 20 mol % to 30 mol %, and R.sub.2O is Na.sub.2O in the amount of 5 mol % to 40 mol %, Li.sub.2O is in the amount of 5 mol % to 40 mol %, K.sub.2O is in the amount of 5 mol % to 40 mol %, or any combination thereof of R.sub.2O.

[0054] In one aspect, a third glass composition includes

(a) P.sub.2O.sub.5 in an amount of 15 mol % to 40 mol %;
(b) Nb.sub.2O.sub.5 is in an amount of 10 mol % to 50 mol %;
(c) at least one alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %;
wherein the glass composition does not include ZnO, B.sub.2O.sub.3, or an alkali metal oxide (R.sub.2O).

[0055] In one aspect, with respect to the third glass composition above, Nb.sub.2O.sub.5 is in the amount of 30 mol % to 40 mol %, TiO.sub.2 is in the amount of 5 mol % to 15 mol %, P.sub.2O.sub.5 is in an amount of 20 mol % to 30 mol %, BaO is in the amount of 5 mol % to 20 mol %, CaO is in the amount of 1 mol % to 10 mol %, and SrO is in the amount of 5 mol % to 20 mol %.

[0056] In one aspect, a fourth glass composition includes

(a) P.sub.2O.sub.5 in an amount of 20 mol % to 40 mol %;
(b) Nb.sub.2O.sub.5 is in an amount of 10 mol % to 50 mol %;
(c) an alkali metal oxide (R.sub.2O) in an amount of 1 mol % to 35 mol %;
(d) an alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %,
wherein the glass composition does not include B.sub.2O.sub.3.

[0057] In one aspect, with respect to the fourth glass composition above, P.sub.2O.sub.5 is in the amount of 25 mol % to 35 mol %; Nb.sub.2O.sub.5 is in the amount of 20 mol % to 35 mol %; ZnO is in the amount of 5 mol % to 25 mol %; R.sub.2O is in the amount of 10 mol % to 35 mol %, and RO is in the amount of 20 mol % to 40 mol %. In a further aspect, the fourth glass composition includes WO.sub.3 in the amount from about 1 mol % to about 15 mol % and/or TiO.sub.2 in the amount from about 1 mol % to about 20 mol %, wherein the sum of Nb.sub.2O.sub.5 with TiO.sub.2 and/or WO.sub.3 is in the amount of 20 mol % to 40 mol %.

[0058] In one aspect, a fifth glass composition includes

(a) P.sub.2O.sub.5 in an amount of 20 mol % to 40 mol %;
(b) Nb.sub.2O.sub.5 is in an amount of 10 mol % to 50 mol %; and
(c) at least one alkali metal oxide (R.sub.2O) in an amount of 5 mol % to 35 mol %;
wherein the glass composition does not include B.sub.2O.sub.3 or an alkaline earth metal oxide (RO).

[0059] In one aspect, with respect to the fifth glass composition above, Nb.sub.2O.sub.5 is in the amount of 30 mol % to 40 mol %, TiO.sub.2 is in the amount of 5 mol % to 15 mol %, P.sub.2O.sub.5 is in an amount of 20 mol % to 35 mol %, ZnO is in the amount of 1 mol % to 15 mol %, and R.sub.2O is in the amount of 1 mol % to 35 mol %, where R.sub.2O is Na.sub.2O, Li.sub.2O, K.sub.2O, or any combination thereof.

[0060] In one aspect, a sixth glass composition includes

(a) P.sub.2O.sub.5 in an amount of 20 mol % to 40 mol %;
(b) Nb.sub.2O.sub.5 is in an amount of 10 mol % to 50 mol %; and
(c) at least one alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %;
wherein the glass composition does not include B.sub.2O.sub.3 or an alkali metal oxide (R.sub.2O).

[0061] In one aspect, with respect to the sixth glass composition above, Nb.sub.2O.sub.5 is in the amount of 30 mol % to 40 mol %, TiO.sub.2 is in the amount of 5 mol % to 15 mol %, P.sub.2O.sub.5 is in an amount of 20 mol % to 35 mol %, ZnO is in the amount of 1 mol % to 15 mol %, and RO is in the amount of 5 mol % to 40 mol %, where RO is BaO, CaO, SrO, or any combination thereof.

[0062] The glass compositions described herein can be prepared using techniques known in the art. In one aspect, the glass compositions disclosed herein can be prepared by melt quenching. In one aspect, P.sub.2O.sub.5 can be added as phosphoric acid (H.sub.3PO.sub.4) in combination with the additional glass-forming components. Further in this aspect, when phosphoric acid is added, the batch materials can be calcined at 350° C. to 400° C. prior to melting. In another aspect, P.sub.2O.sub.5 can be added as anhydrous phosphorus pentoxide. In one aspect, the batch materials are melted at 900° C. to 1,300° C. In another aspect, the batch materials are melted in platinum crucibles.

[0063] The glass compositions described herein have a refractive index suitable for the use in optical articles. In one aspect, the glass compositions have a refractive index of at least 1.75 at 587.6 nm (D-line) at 25° C., or a refractive index at 587.6 nm at 25° C. of about 1.75, 1.80, 1.85, 1.90, 1.95, or 2.00, where any value can be a lower- and upper-endpoint of a range (e.g., 1.75 to 1.95, 1.90 to 2.00, etc.).

[0064] The glass compositions described herein have a density suitable for the use in optical articles. The density is sufficiently low such that they can be used in virtual reality or augmented reality headsets and other optical articles. In one aspect, the glass compositions have a density of less than or equal to 4.0 g/cm.sup.3, or a density of 3.5 g/cm.sup.3, 3.6 g/cm.sup.3, 3.7 g/cm.sup.3, 3.8 g/cm.sup.3, 3.9 g/cm.sup.3, or 4.0 g/cm.sup.3, where any value can be a lower- and upper-endpoint of a range (e.g., 3.5 g/cm.sup.3 to 3.9 g/cm.sup.3, 3.75 g/cm.sup.3 to 4.0 g/cm.sup.3, etc.).

[0065] The glass compositions described herein have a glass thermal stability index that permits the manufacture of optical articles using a number of different glass-making techniques. Not wishing to be bound by theory, the greater the glass thermal stability index the larger the window exists for glass processing with less chance of devitrification. In one aspect, the glass compositions have a glass thermal stability index of greater than or equal to 200° C., greater than or equal to 225° C., or a glass thermal stability index of 200° C., 210° C., 220° C., 230° C., 240° C., 250° C., 260° C., 270° C., 280° C., 290° C., or 300° C., where any value can be a lower- and upper-endpoint of a range (e.g., 200° C. to 300° C., 220° C. to 270° C., etc.).

[0066] In certain aspects, the glass composition does not crystallize when heated at the rate of 10° C./min normally utilized in the characterization by differential scanning calorimetry. In these aspects, there is no value for T.sub.x and the glass composition does not have a glass thermal stability index as defined herein. With respect to these glass compositions, they are desirable from the standpoint of their forming characteristics, especially when the forming technique used requires a reheating step.

[0067] In one aspect, the glass compositions described herein have an Abbe number of at least 20, or from 20 to 40. In another aspect, the Abbe number is about 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40, where any value can be a lower- and upper-endpoint of a range (e.g., 25 to 35, 30 to 40, etc.).

[0068] In one aspect, the glass compositions disclosed herein have annealing points of from about 450° C. to about 750° C. In another aspect, the annealing point of the glass composition is about 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 725, or 750, ° C., where any value can be a lower- and upper-endpoint of a range (e.g., 450° C. to 700° C., 500 to 650° C., 600° C. to 700° C., 650 to 750° C., etc.).

[0069] In one aspect, the glass compositions described herein have a coefficient of thermal expansion of from about 6.0 ppm/° C. to about 12.0 ppm/° C. at each temperature over a range extending from room temperature to 300° C. In one aspect, the coefficient of thermal expansion is about 7.5, 8, 8.5, 9, 9.5, 10, 10.5, or 11 ppm/° C., where any value can be a lower- and upper-endpoint of a range (e.g., 8 to 10 ppm/° C., 8.5 to 10.5 ppm/° C., etc.).

[0070] In one aspect, the glass compositions have a softening point of 575° C. to 850° C. as determined by ASTM C1351M. In another aspect, the softening point of the glass composition is about 575, 600, 625, 650, 675, 700, 725, 750, 775, 800, 825, or 850° C., where any value can be a lower- and upper-endpoint of a range (e.g., 600° C. to 700° C., 650 to 750° C., etc.).

[0071] In one aspect, the glass compositions have an internal liquidus temperature of 875° C. to 1,200° C. In another aspect, the internal liquidus temperature of the glass composition is about 875, 900, 925, 950, 975, 1,000, 1,025, 1,050, 1,075, 1,100, 1,125, 1,150, or 1,200° C., where any value can be a lower- and upper-endpoint of a range (e.g., 900° C. to 1,100° C., 1,000 to 1,150° C., etc.).

[0072] In one aspect, the glass compositions have a Young's modulus of 50 GPa to 110 GPa. In another aspect, the Young's modulus of the glass composition is about 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, or 110 GPa, where any value can be a lower- and upper-endpoint of a range (e.g., 60 to 80 GPa, 70 to 90 GPa, etc.).

[0073] In other aspects, the color of the glass composition can be controlled. Not wishing to be bound by theory, the oxidation of multi-valence transition metal cations during glass production can discolor the final glass composition. Depending on the valence states of the transition metals, the color of the glass compositions containing Nb, Ti, and W can vary from light yellow, dark brown to deep blue. In one aspect, discoloration of the glass composition can be achieved by heating the glass composition at or near its glass transition temperature (T.sub.g) in air or an atmosphere oxygen. In one aspect, the glass composition is heated 120° C. above the glass transition temperature for 10 to 1440 minutes in air or under an atmosphere of oxygen. The heat-treatment does not adversely affect the transmittance of the glass and as shown in the Examples, the transmittance and refractive index of the glass composition can be improved with the heat-treatment.

[0074] In another aspect, a component such as CeO.sub.2 can be added during glass formation in order to reduce discoloration of the glass composition. In one aspect, the amount of CeO.sub.2 that can be used is from 0.001 mol % to 2 mol %. As shown in the Examples, the glass transmittance and refractive index of the glass can be improved with the addition of CeO.sub.2.

[0075] In one aspect, the glass compositions described herein are stable enough that they can be cast into large shapes approximately 1 cm thick and cooled to glass without devitrification.

[0076] In one aspect, the glass compositions disclosed herein exhibit chemical durability comparable to silicate compositions with similar refractive index. In another aspect, although typical phosphate glasses corrode under high moisture/high humidity conditions, the glasses disclosed herein do not deteriorate in this manner. In another aspect, the glass compositions disclosed herein have low dispersion in addition to high refractive index.

[0077] In one aspect, the glass compositions described herein can be used to produce optical articles. In one aspect, the optical article is transparent. In another aspect, the glasses provided herein may be strongly colored when formed by conventional melting in air but the color can be removed. In one aspect, the color is removed by annealing the glasses in air or oxygen at temperatures near T.sub.g for the glass compositions. In another aspect, the color is removed by the addition of an oxidation agent, e.g. CeO.sub.2.

[0078] In another aspect, the glass compositions can be processed by various techniques into a powder, fiber, beads, sheets, or three-dimensional scaffolds or shapes. Glasses with desired properties and forms can be used for their applications in optical displays, augmented reality devices or virtual reality devices, non-linear photonic materials, sealing glasses, encapsulating glass for optical objects, separators in batteries, optical amplification and waveguide devices.

EXAMPLES

[0079] The following examples are put forth to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, and methods described and claimed herein are made and evaluated, and are intended to be purely exemplary and are not intended to limit the scope of the discoveries disclosed herein. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in ° C. or is at ambient temperature, and pressure is at or near atmospheric. Numerous variations and combinations of reaction conditions (e.g., component concentrations, desired solvents, solvent mixtures, temperatures, pressures, and other reaction ranges and conditions) can be used to optimize the product purity and yield obtained from the described process. Only reasonable and routine experimentation will be required to optimize such process conditions.

Example 1: Production of Glass Compositions

[0080] The glass compositions were prepared by standard melt-quench methodology from batches of metal oxide powders, metal carbonate powders and metal phosphate compound powders. P.sub.2O.sub.5 was added to the batch as phosphate compounds, e.g., lithium phosphate, sodium hexametaphosphate, potassium phosphate, calcium phosphate, barium phosphate, and/or phosphoric acid (H.sub.3PO.sub.4). The addition of phosphoric acid required calcining the batches at 350-400° C. prior to melting at 900-1,300° C. in platinum crucibles in air for 2-4 hours. Glasses, once formed, were annealed at annealing temperature or near the glass transition temperature (T.sub.g) in air for about 2 hours then subsequently quenched to reduce internal stress. The glass compositions were not subsequently remelted. The glass compositions were not subsequently cleaned or subjected to post-fabrication processing. Following annealing, properties such as thermal expansion coefficient, T.sub.g, refractive index, density, and others were determined.

Example 2: Sample Glass Compositions and Characterization

[0081] Several glass compositions were prepared and their properties are presented in Tables 1-9, where the amount of each component is expressed in mol %.

[0082] The following parameters in the tables below are defined as follows:

[0083] Density. The density was measured according to ASTM C693.

[0084] Refractive Index (RI) and Abbe Number (V.sub.d). RI was measured with a Metricon Model 2010 Prism Coupler instrument. RI measurements were performed on the Metricon Model 2010 Prism Coupler at wavelengths of 406 nm, 473 nm, 532 nm, 633 nm, 790 nm and 981 nm using various laser sources. The Metricon 2010 prism coupler operates as a fully automated refractometer, in which the refractive index of bulk materials and/or films can be measured. Refractive indices of bulk materials, such as the provided glass samples, are measured by the Metricon 2010 Prism Coupler. Measured index of refraction results were fit to a Cauchy or Sellmeier dispersion equation and constants were determined. The refractive index for optical glasses is specified herein at a wavelength of 587.6 nm and referred to as R.sub.d and/or nD in the tables below. When refractive index was measured at a different wavelength, it is noted as n519, n532, n633, and the like, where the number indicates the wavelength in nanometers. Using fitted index dispersion values, the V.sub.D Abbe number was calculated for each glass composition.

[0085] Strain point and Annealing Point. The beam bending viscosity method measures the viscosity of inorganic glass from 10.sup.12 to 10.sup.14 poise versus temperature and from this measurement, estimates of the strain point and annealing point of the glass are obtained according to ASTM C598.

[0086] Softening Point. The parallel place viscosity method measures viscosity from 10.sup.7 to 10.sup.9 poise versus temperature and from this measurement, estimates of a “normal softening point” of the glasses was obtained. This method is similar to ASTM C1351M.

[0087] Coefficient of Thermal Expansion (CTE). A dilatometer method was used to determine a mean coefficient of linear thermal expansion (CTE) of the glasses according to ASTM E228.

[0088] Glass Transition Temperature (T.sub.g) and Onset Temperature of Crystallization (T.sub.x). T.sub.g and T.sub.x were measured by differential scanning calorimetry (DSC) with ramp rate of 10° C./min to 1000° C. in Argon atmosphere. Samples were pulverized with a mortar and pestle. About 30 mg was used for analysis. Samples were weighed using a microbalance and placed into a Netzsch DSC 404 F1 Pegasus instrument for analysis. The atmosphere was evacuated and backfilled in with Argon to provide an inert atmosphere.

[0089] Liquidus Temperature. The liquidus temperature was measured by the gradient furnace method. This method conforms to the ASTM C829-81 Standard Practices for Measurement of Liquidus Temperature of Glass.

[0090] Poisson's Ratio, Shear Modulus, and Young's Modulus. Young's modulus, shear modulus and Poisson's ratio were measured by Resonant Ultrasound Spectroscopy, and the instrument model is Quasar RUSpec 4000 by Magnaflux.

[0091] The following procedures were used for the Advanced Optics (AO) Test and Nano Strip 2× Test to evaluate the chemical durability of each glass. The results provided in the tables below.

[0092] Advanced optics (AO) tests were performed to evaluate the chemical durability of the glass compositions. AO tests are typically performed in evaluating optical glasses. Each glass sample (25 mm×25 mm×1 mm, surface polished) was etched in 10 wt % HCl for 10 min at 25° C. The ratio of surface area to volume used in this test is 0.33 cm.sup.−1. After etching for 10 minutes, the samples were quenched in deionized water and rinsed in 18 MΩ water, and then dried by high-pure nitrogen gas and placed in a desiccator for overnight. Weight loss normalized to surface area (mg/cm.sup.2 or mg/mm.sup.2) and weight loss percentage (wt %) were calculated.

[0093] Nano Strip 2× Test. The dried samples were submerged in 600 ml of Nanostrip 2× solution (Capitol Scientific, 85% H.sub.2SO.sub.4 and <1% H.sub.2O.sub.2) for 50 min at 70° C. with a stir at 400 rpm speed. The ratio of surface area to volume used in this test is 0.08 cm.sup.−1. After 50 minutes, the samples were quenched in deionized water and rinsed in 18 MΩ water, and then dried by high-pure nitrogen gas and placed in a desiccator for overnight. weight loss normalized to surface area (mg/cm.sup.2) and weight loss percentage (wt %) was calculated.

TABLE-US-00001 TABLE 1 Component 1 2 3 4 5 6 7 8 Al.sub.2O.sub.3 4.8 4.8 4.8 4.8 P.sub.2O.sub.5 30.0 30.0 30.8 30.3 30.6 29.9 30.2 30.1 Na.sub.2O 15.0 20.0 15.6 20.0 14.9 14.9 14.8 15.0 Li.sub.2O + Na.sub.2O + 15.0 20.0 15.6 20.0 14.9 14.9 14.8 15.0 K.sub.2O BaO 10.0 5.0 10.0 5.1 10.1 10.4 9.9 10.1 ZnO 20.0 10.0 19.4 9.9 20.0 5.0 10.0 15.0 MgO + CaO + 30.0 15.0 29.4 15.0 30.1 15.4 19.9 25.1 BaO + SrO + ZnO R.sub.2O + RO + 45.0 35.0 45.0 35.0 45.0 30.3 34.7 40.1 ZnO TiO.sub.2 10.0 10.0 15.0 10.4 5.2 Nb.sub.2O.sub.5 25.0 25.0 24.1 24.7 19.6 19.9 19.9 19.7 Nb.sub.2O.sub.5 + TiO.sub.2 + 25.0 35.0 24.1 34.7 19.6 34.9 30.3 24.9 WO.sub.3 Properties Density (g/cm.sup.3) 3.726 3.561 3.726 3.561 3.633 3.551 3.583 3.611 nD 1.811.sup.a 1.844.sup.a 1.811 1.844 1.761 1.832 1.807 1.788 V.sub.d 30.37 22.40 27.30 23.99 25.24 28.28 Strain Point (° C.) 526 559 502 568 544 520 Annealing Point 562 593 538 604 581 556 (° C.) Softening Point 686 714 668 729 707 687 (° C.) CTE (<300° C., 7.9 7.9 8.1 8.0 7.9 8.0 on heating) in ppm/° C. T.sub.g onset (° C.) 552 604 552 604 544 618 589 566 T.sub.x onset (° C.) 807 825 807 825 766 850 810 794 T.sub.x onset − T.sub.g onset 255 221 255 221 222 232 221 228 (° C.) Liquidus internal 1090 1045 1035 1085 1070 1055 (° C.) AO weight loss 4.0 × 10.sup.−4 1.0 × 10.sup.−3 2.5 × 10.sup.−5 3.2 × 10.sup.−5 2.5 × 10.sup.−5 3.2 × 10.sup.−5 (mg/mm.sup.2), Nanostrip 1.2 × 10.sup.−4 4.1 × 10.sup.−5 8.4 × 10.sup.−4 2.5 × 10.sup.−4 3.3 × 10.sup.−4 1.1 × 10.sup.−3 (mg/mm.sup.2), Poissons Ratio 0.256 0.24 0.254 0.239 0.244 0.255 Shear Modulus 33.3 35.8 32.0 36.3 34.9 33.4 (GPa) Young's Modulus 83.6 88.6 80.3 89.9 87.0 83.9 (GPa) .sup.aEstimate based on similar compositions.

TABLE-US-00002 TABLE 2 Component 9 10 11 12 13 14 15 16 17 18 P.sub.2O.sub.5 30 30 30 30 30 25 25 30.5 35.1 25.3 Li.sub.2O 5 3 5 5 Na.sub.2O 15 15 5 3 5 5 33.5 19.9 24.7 K.sub.2O 5 3 5 5 Li.sub.2O + Na.sub.2O + 15 15 15 9 0 15 15 33.5 19.9 24.7 K.sub.2O CaO 15 18 5 15 15 BaO 10 15 18 15 15 15 11.3 20 24.8 SrO 30 15 ZnO 20 10 MgO + CaO + 30 30 30 36 45 30 30 11.3 20 24.8 BaO + SrO + ZnO) R.sub.2O + RO + 45 45 45 45 45 45 45 44.8 39.9 49.5 ZnO TiO.sub.2 10.0 Nb.sub.2O.sub.5 20 25 25 25 25 15 25 24.7 25 25.2 WO.sub.3 5 5 5 Nb.sub.2O.sub.5 + 25 25 25 25 25 30 30 24.7 25 25.2 TiO.sub.2 + WO.sub.3 CeO.sub.2 0.1 0.1 0.1 0.1 0.1 Properties Density 3.819 3.717 3.633 3.674 3.81 3.745 3.748 3.51 3.631 3.663 (g/cm.sup.3) nD 1.788 1.793 1.807 1.816 1.832 1.812 1.851 1.754 1.757 1.799 V.sub.d 26.34 27.94 28.85 26.64 28.56 25.83 24.18 27.84 29.13 27.06 Strain Point 533.5 547.2 (° C.) Annealing 570.2 578.5 Point (° C.) Softening 667.9 716.8 739.3 739.5 742.8 666.9 691.3 654.7 698.5 682 Point (° C.) T.sub.g onset (° C.) 551.8 620.7 588.7 603 619.4 572.9 576.9 563.5 586.4 590.8 T.sub.x onset (° C.) 839.1 850.2 831 832.1 827.4 812.8 809.7 861.3 793 793.7 T.sub.x onset − T.sub.g onset 287.3 229.5 242.3 229.1 208 239.9 232.8 297.8 206.6 202.9 (° C.) Nanostrip 4.0 × 10.sup.−4 1.3 × 10.sup.−2 7.0 × 10.sup.−4 2.8 × 10.sup.−3 1.4 × 10.sup.−3 (mg/mm.sup.2) Poissons 0.262 0.27 Ratio Shear 28.7 29.7 Modulus (GPa) Young's 72.6 75.4 Modulus (GPa)

TABLE-US-00003 TABLE 3 Component 19 20 21 22 23 24 25 26 27 28 29 30 P.sub.2O.sub.5 30 25 25 25 30 30 30 25 30 27.5 27.5 27.5 Li.sub.2O 5 6 5 5 7 5 7 5 7 5 7 8 Na.sub.2O 5 6 5 5 7 5 7 5 7 5 7 9 K.sub.2O 5 5.5 5 5 6 5 6 5 6 5 6 8 Li.sub.2O + Na.sub.2O + 15 17.5 15 15 20 15 20 15 20 15 20 25 K.sub.2O CaO 10 12.5 12.5 12.5 8 10 8 12.5 8 11 9.5 7.5 BaO 10 12.5 12.5 12.5 9 10 9 12.5 9 11.5 10 7.5 SrO 10 10 10 10 8 0 0 10 8 10 8 7.5 ZnO 10 8 MgO + CaO + 30 35 35 35 25 30 25 35 25 32.5 27.5 22.5 BaO + SrO + ZnO R.sub.2O + RO + 45 52.5 50 50 45 45 45 50 45 47.5 47.5 47.5 ZnO TiO.sub.2 5 10 15 10 10 10 10 Nb.sub.2O.sub.5 25 22.5 20 15 25 25 25 10 15 15 15 15 Nb.sub.2O.sub.5 + 25 22.5 25 25 25 25 25 25 25 25 25 25 TiO.sub.2 + WO.sub.3 Properties Density 3.692 3.781 3.77 3.7 3.627 3.675 3.623 3.634 3.497 3.648 3.564 3.473 (g/cm.sup.3) nD 1.805 1.803 1.810 1.791 1.798 1.816 1.807 1.773 1.765 1.784 1.776 1.765 T.sub.g onset 591 577 587 582 568 564 548 581 554 587 559 543 (° C.) T.sub.x onset 856 783 791 806 783 833 837 781 816 795 771 762 (° C.) T.sub.x onset − 265 206 204 224 215 269 289 201 261 209 211 219 T.sub.g onset (° C.)

TABLE-US-00004 TABLE 4 Component 31 32 33 34 35 36 37 38 P.sub.2O.sub.5 33.2 32.1 32.6 33 31.7 32.3 33.1 28.2 Li.sub.2O 10.1 Na.sub.2O 18.3 14 21.5 18.1 13.8 21.4 21.3 8.7 K.sub.2O 5.1 Li.sub.2O + Na.sub.2O + K.sub.2O 18.3 14 21.5 18.1 13.8 21.4 21.3 23.9 MgO 7 14.9 7.1 14.1 BaO 18.7 15.3 15.3 18.5 15.2 15 7.5 11.2 SrO 10.3 ZnO 5.6 13.7 5.6 MgO + CaO + BaO + 24.3 29 20.9 25.5 30.1 22.1 21.6 21.5 SrO + ZnO R.sub.2O + RO + ZnO 42.6 43 42.4 43.6 43.9 43.5 42.9 45.4 Nb.sub.2O.sub.5 24.2 24.9 25 23.4 24.4 24.2 24 26.5 Nb.sub.2O.sub.5 + TiO.sub.2 + WO.sub.3 24.2 24.9 25 23.4 24.4 24.2 24 26.5 Properties Density (g/cm.sup.3) 3.691 3.705 3.631 3.661 3.649 3.6 3.431 3.718 nD 1.803 1.788 1.789 1.813 1.799 1.812 1.789 1.794 V.sub.d 25.26 26.69 21.45 26.14 25.45 23.96 26.49 28.25 CTE (<300° C., on heating) 9.6 8.6 10.1 9.8 8.8 10.2 9.6 11.4 in ppm/° C. T.sub.g onset (° C.) 564 575 567 589 610 580 586 548 T.sub.x onset (° C.) 811 819 810 824 826 839 860 761 T.sub.x onset − T.sub.g onset (° C.) 247 244 243 235 216 259 274 213

TABLE-US-00005 TABLE 5 Component 39 40 41 42 43 44 45 46 P.sub.2O.sub.5 25 27.5 30 25.8 26 26 25.6 32.1 Li.sub.2O 7 7 7 9.5 10.1 9.6 9.5 Na.sub.2O 8 8 8 10 9.8 9.9 10 19.6 K.sub.2O 5 5 5 5 4.7 4.8 4.8 Li.sub.2O + Na.sub.2O + K.sub.2O 20 20 20 24.5 24.6 24.3 24.3 19.6 CaO 15 8.75 7.5 4.9 4.9 4.9 5 BaO 15 8.75 7.5 10.3 10.1 10.2 10.2 5 SrO 9.1 9.6 4.6 4.7 ZnO 10 10 4.9 8.9 MgO + CaO + 30 27.5 25 24.3 24.6 19.7 24.8 13.9 BaO + SrO + ZnO R.sub.2O + RO + ZnO 50 47.5 45 48.8 49.2 44 49.1 33.5 TiO.sub.2 5.1 10 9.9 Nb.sub.2O.sub.5 20 25 25 20.2 19.8 15 15.1 24.5 WO.sub.3 5 5 5.1 10.1 Nb.sub.2O.sub.5 + TiO.sub.2 + 25 25 25 25.3 24.8 30.1 25.2 34.4 WO.sub.3 CeO.sub.2 0.01 0.01 Properties Density (g/cm.sup.3) 3.843 3.688 3.595 3.662 3.781 3.681 3.881 3.512 nD 1.801 1.822 1.808 1.798 1.787 1.800 1.765 1.861 V.sub.d 26.71 27.57 25.86 22.00 T.sub.g onset (° C.) 547 540 539 543 522 529 489 610 T.sub.x onset (° C.) 772 783 826 762 764 788 827 T.sub.x onset − T.sub.g onset 225 243 287 219 242 259 a 216 (° C.) .sup.a. No crystallization peak in DSC.

TABLE-US-00006 TABLE 6 Component 47 48 49 50 51 P.sub.2O.sub.5 30.0 30.0 30.0 30.0 30.0 Na.sub.2O 15.0 15.0 15.0 15.0 15.0 Li.sub.2O + Na.sub.2O + K.sub.2O 15.0 15.0 15.0 15.0 15.0 BaO 10 10 10 15 20 ZnO 20 15 10 15 10 MgO + CaO + 30 25 20 30 30 BaO + SrO + ZnO R.sub.2O + RO + ZnO 45 40 35 45 45 Nb.sub.2O.sub.5 20 25 30 20 20 WO.sub.3 5 5 5 5 5 Nb.sub.2O.sub.5 + TiO.sub.2 + WO.sub.3 25 30 35 25 25 Properties Density (g/cm.sup.3) 3.818 3.853 3.885 3.862 3.959 nD 1.785 1.820 1.860 1.780 1.790 T.sub.gonset (° C.) 547 575 606 552 580 T.sub.xonset (° C.) 818 827 837 801 809 T.sub.xonset − T.sub.gonset (° C.) 271 252 231 250 230

TABLE-US-00007 TABLE 7 Mol % Component 52 53 54 55 56 57 58 59 60 61 62 63 P.sub.2O.sub.5 30 30 30 30 30 30 30 30 30 25 25 30 Li.sub.2O 5 5 5 7 7 7 7 7 8.75 7 7 Na.sub.2O 10 5 20 10 7 7 7 8 8 10 8 8 K.sub.2O 5 5 5 6 6 6 5 5 6.25 5 5 Li.sub.2O + Na.sub.2O + 20 15 20 20 20 20 20 20 20 25 20 20 K.sub.2O CaO 10 7.36 6.08 4.8 8 8 8 10 10 BaO 10 15 5 5 8.28 6.84 5.4 9 9 9 9.99 10 SrO 5 8 10 ZnO 5 10 10 7.36 6.08 4.8 8 8 10 MgO + CaO + 20 25 15 15 23 19 15 25 25 25 29.99 30 BaO + SrO + ZnO R.sub.2O + RO + 40 40 35 35 43 39 35 45 45 50 49.99 50 ZnO TiO.sub.2 5 10 10 20 5 10 15 15 Nb.sub.2O.sub.5 15 15 25 15 25 25 25 20 15 10 10 20 WO.sub.3 10 5 2 6 10 Nb.sub.2O.sub.5 + 30 30 35 35 27 31 35 25 25 25 25 20 TiO.sub.2 + WO.sub.3 CeO.sub.2 0.01 0.01 0.001 0.001 0.01 Properties Density 3.752 3.671 3.534 3.399 3.597 3.673 3.755 3.55 3.48 3.477 3.56 3.577 (g/cm.sup.3) nD 1.765 1.78 1.82 1.805 1.795 1.805 1.82 1.789 1.771 1.756 1.766 1.764 T.sub.g onset (° C.) 524 574 610 569 542 541 547 535 526 525 548 517 T.sub.x onset (° C.) 800 778 824 789 806 810 786 776 803 808 T.sub.x onset − 276 204 214 220 264 268 239 241 277 a a 291 T.sub.g onset (° C.) .sup.a. No crystallization peak in DSC.

TABLE-US-00008 TABLE 8 Comp. 64 65 66 67 68 69 70 71 72 73 74 75 76 77 P.sub.2O.sub.5 25.7 25.6 25.8 25.4 25.7 30 30 30 30 30 30 30 30.0 29.3 Li.sub.2O 10 9.9 10 10 10 7 7 7 7 7 7 7 6.9 6.8 Na.sub.2O 10.3 10.4 10.3 10.4 10.6 8 8 8 8 8 8 8 7.0 7.1 K.sub.2O 5.1 5 5 5.1 4.7 5 5 5 5 5 5 5 5.9 6.0 R.sub.2O Li.sub.2O + 25.4 25.3 25.3 25.5 25.3 20 20 20 20 20 20 20 19.8 20.0 Na.sub.2O + K.sub.2O MgO 0.2 CaO 4.9 4.9 4.9 4.8 4.9 12 12 10.5 9 10 12 12 7.8 7.9 BaO 10.1 10.2 10.1 10.2 10.1 10 10 8.5 7 10 10 10 9.2 9.2 SrO 4.6 5 4.7 4.8 4.9 ZnO 4.5 4.5 4.5 7 6.9 5 5 8 11 5 5 5 8.1 8.5 MgO + 24.1 24.6 24.2 26.8 26.8 27 27 27 27 25 27 27 25.3 25.6 CaO + BaO + SrO + ZnO R.sub.2O + 49.5 49.9 49.5 52.3 52.1 47 47 47 47 45 47 47 45.1 45.6 RO + ZnO La.sub.2O.sub.3 1 2 Nb.sub.2O.sub.5 14.6 16.9 19.7 14.8 17.1 20.5 18 18 18 23 22 21 24.9 25.0 WO.sub.3 10.1 7.6 5.1 7.5 5.1 2.5 5 5 5 Nb.sub.2O.sub.5 + 24.7 24.5 24.8 22.3 22.2 23 23 23 23 23 22 21 24.9 25.0 TiO.sub.2 + WO.sub.3 SnO 2 La.sub.2O.sub.3 + 1 2 Ta.sub.2O.sub.5 + Y.sub.2O.sub.3 + HfO.sub.2 Properties Density 3.855 3.824 3.791 3.809 3.774 3.620 3.645 3.644 3.637 3.622 3.622 3.652 3.609 3.629 (g/cm.sup.3) nD 1.767 1.777 1.793 1.760 1.771 1.773 1.761 1.760 1.764 1.789 1.783 1.779 1.804 1.808 V.sub.d 29.39 29.01 27.67 29.65 29.00 Annealing 517 506 496 494 532 Point (° C.) T.sub.g onset 489 499 511 484 495 528 517 508 503 551 543 542 553 551 (° C.) T.sub.x onset 747 735 719 850 777 840 822 (° C.) T.sub.x onset − a 248 224 a 225 322 a a a a 234 a 287 271 T.sub.g onset (° C.) Nanostrip 9.9 × 9.9 × 1.8 × 7.5 × (mg/mm.sup.2) 10.sup.−4 10.sup.−4 10.sup.−3 10.sup.−4 .sup.a. No crystallization peak in DSC.

TABLE-US-00009 TABLE 9 Mol % Component 78 79 80 81 82 Al.sub.2O.sub.3 0.2 0.1 0.1 P.sub.2O.sub.5 30.9 31.2 30.8 30.6 30.6 Na.sub.2O 33.1 32.2 19.8 20.4 19.7 Li.sub.2O + Na.sub.2O + K.sub.2O 33.1 32.2 19.8 20.4 19.7 BaO 11.5 11.6 5.0 5.0 5.0 ZnO 9.9 9.8 9.9 MgO + CaO + 11.5 11.6 15.0 14.8 14.9 BaO + SrO + ZnO R.sub.2O + RO + ZnO 44.6 43.7 34.8 35.2 34.6 TiO.sub.2 9.9 9.9 10.0 Nb.sub.2O.sub.5 24.3 24.9 24.5 24.3 24.6 Nb.sub.2O.sub.5 + TiO.sub.2 + WO.sub.3 24.3 24.9 34.4 34.2 34.6 CeO.sub.2 0.1 Properties Density (g/cm.sup.3) 3.515 3.509 3.426 3.385 3.563 nD 1.754 1.753 1.844 1.846 1.842 T.sub.gonset (° C.) 557 566 612 614 608 T.sub.xonset (° C.) 846 845 845 T.sub.xonset − T.sub.gonset (° C.) a a 234 231 237 a No crystallization peak in DSC.

TABLE-US-00010 TABLE 10 Mol % Component 83 84 85 86 87 88 89 90 91 92 B.sub.2O.sub.3 2.5 5.0 2.8 2.8 2.8 2.5 2.5 5.0 P.sub.2O.sub.5 30.0 27.5 25.0 25.3 25.1 25.0 30.0 30.0 30.0 30.0 Li.sub.2O 7.0 7.0 7.0 10.0 8.9 9.8 10.2 7.9 8.4 7.3 Na.sub.2O 8.0 8.0 8.0 9.7 9.4 9.7 10.2 7.9 8.4 7.3 K.sub.2O 5.0 5.0 5.0 4.2 3.8 4.2 4.5 3.5 3.8 3.3 Li.sub.2O + Na.sub.2O + K.sub.2O 20.0 20.0 20.0 23.9 22.1 23.7 25.0 19.3 20.6 17.9 CaO 12.0 12.0 12.0 4.9 4.9 4.9 2.8 4.4 4.7 4.1 BaO 10.0 10.0 10.0 9.1 9.4 9.2 5.0 7.9 8.4 7.3 SrO 4.9 3.8 5.1 2.2 3.5 3.8 3.3 ZnO 5.0 5.0 5.0 7.0 4.6 4.6 5.0 5.0 5.0 5.0 MgO + CaO + BaO + 27.0 27.0 27.0 25.9 22.7 23.8 15.0 20.8 21.9 19.6 SrO + ZnO R.sub.2O + RO + ZnO 47.0 47.0 47.0 49.8 44.8 47.5 40.0 40.0 42.5 37.5 Nb.sub.2O.sub.5 23.0 23.0 23.0 14.6 17.2 17.0 17.5 17.5 17.5 17.5 WO.sub.3 7.6 9.9 7.5 10.0 10.0 10.0 10.0 Nb.sub.2O.sub.5 + TiO.sub.2 + WO.sub.3 23.0 23.0 23.0 22.2 27.1 24.5 27.5 27.5 27.5 27.5 Properties Density (g/cm.sup.3) 3.590 3.608 3.642 3.788 3.875 3.801 3.658 3.758 3.783 3.729 nD 1.787 1.797 1.807 1.761 1.796 1.782 1.760 1.770 1.772 1.772 V.sub.d 30.31 27.26 28.73 Strain Point (° C.) 464 Annealing Point (° C.) 498 Softening point (° C.) 613 T.sub.g onset (C) 542 529 524 483 503 497 492 514 512 518 T.sub.x onset (C) 807 790 767 815 786 T.sub.x onset − T.sub.g onset 265 262 243 a a a a 302 a 268 (° C.) .sup.a. No crystallization peak in DSC.

TABLE-US-00011 TABLE 11 Mol % Component 93 94 95 96 97 98 99 100 101 102 B.sub.2O.sub.3 7.5 2.5 2.5 2.8 2.9 2.8 P.sub.2O.sub.5 30.0 30.0 30.0 25.0 25.0 24.7 24.6 25.1 24.9 25.1 Li.sub.2O 6.8 8.4 7.3 10.0 10.0 9.5 9.7 8.3 8.8 8.5 Na.sub.2O 6.8 8.4 7.3 10.0 10.0 9.9 9.5 8.7 8.9 8.7 K.sub.2O 3.0 3.8 3.3 5.0 5.0 4.9 4.8 3.8 4.0 3.7 Li.sub.2O + Na.sub.2O + K.sub.2O 16.5 20.6 17.9 25.0 25.0 24.3 24.0 20.7 21.7 21.0 CaO 3.8 4.7 4.1 5.0 5.0 5.1 5.1 5.1 5.0 5.1 BaO 6.8 8.4 7.3 10.0 10.0 9.9 10.1 9.0 9.0 9.1 SrO 3.0 3.8 3.3 5.0 5.0 4.9 5.0 4.0 3.9 3.9 ZnO 5.0 5.0 5.0 5.0 5.0 5.4 5.4 5.0 5.0 5.1 MgO + CaO + BaO + 18.5 21.9 19.6 25.0 25.0 25.3 25.6 23.1 22.9 23.2 SrO + ZnO R.sub.2O + RO + ZnO 35.0 42.5 37.5 50.0 50.0 49.6 49.6 43.8 44.6 44.1 TiO.sub.2 4.7 5.5 Nb.sub.2O.sub.5 17.5 17.5 17.5 11.9 6.9 15.4 15.4 18.0 17.4 17.6 WO.sub.3 10.0 7.5 12.5 8.5 12.6 10.3 10.3 10.2 10.0 10.1 Nb.sub.2O.sub.5 + TiO.sub.2 + WO.sub.3 27.5 25.0 30.0 25.0 25.0 25.7 25.7 28.2 27.4 27.8 CeO.sub.2 0.02 0.2 0.02 0.2 0.2 Properties Density (g/cm.sup.3) 3.702 3.677 3.814 3.809 3.895 3.878 3.896 3.860 3.865 3.656 nD 1.770 1.760 1.785 1.775 1.755 1.772 1.775 1.795 1.792 1.760 V.sub.d Strain Point (° C.) 462 479 Annealing Point (° C.) 497 513 T.sub.g onset (° C.) 519 507 521 500 472 493 493 504 505 506 T.sub.x onset (° C.) 767 782 729 T.sub.x onset − T.sub.g onset (° C.) 249 a 262 228 a a a a a a a. No crystallization peak in DSC.

TABLE-US-00012 TABLE 12 Mol % Component 103 104 105 106 107 108 109 110 111 112 B.sub.2O.sub.3 2.8 2.8 2.8 2.8 P.sub.2O.sub.5 30.1 25.2 25.1 25.1 30.3 30.4 30.2 25.4 25.5 25.4 Li.sub.2O 8.4 9.8 9.9 10.0 6.9 6.8 6.9 9.1 9.1 9.0 Na.sub.2O 8.5 10.2 10.2 10.2 7.6 7.5 7.6 9.0 9.0 9.0 K.sub.2O 3.7 4.8 4.9 4.9 5.9 5.9 5.9 3.9 3.9 3.9 Li.sub.2O + Na.sub.2O + K.sub.2O 20.6 24.8 25.0 25.1 20.4 20.2 20.4 22.0 22.0 22.0 CaO 4.8 5.1 5.1 5.0 7.7 7.7 7.7 4.8 4.8 4.8 BaO 8.4 10.1 10.1 10.1 9.1 9.1 9.0 9.1 9.1 9.1 SrO 3.5 4.9 4.9 4.9 3.8 3.9 3.9 ZnO 5.0 4.6 4.6 4.6 7.3 7.3 7.2 5.1 4.9 4.9 MgO + CaO + BaO + 21.6 24.7 24.7 24.6 24.1 24.1 23.9 22.9 22.8 22.7 SrO + ZnO R.sub.2O + RO + ZnO 42.2 49.5 49.7 49.7 44.5 44.3 44.3 44.9 44.8 44.7 Nb.sub.2O.sub.5 17.4 14.6 14.6 14.5 24.3 24.5 24.7 17.3 17.3 17.4 WO.sub.3 7.5 10.3 10.2 10.2 9.6 9.6 9.7 Nb.sub.2O.sub.5 + TiO.sub.2 + WO.sub.3 24.9 24.9 24.8 24.7 24.3 24.5 24.7 27.0 26.9 27.1 CeO.sub.2 0.02 Ta.sub.2O.sub.5 0.4 0.4 0.4 0.7 0.7 0.7 Properties Density (g/cm.sup.3) 3.675 3.842 3.816 3.863 3.594 3.590 3.597 nD 1.760 1.768 1.804 1.790 1.790 1.794 Strain Point (° C.) 446 501 Annealing Point (° C.) 478 537 Softening point (° C.) 591 671 CTE (<300° C., on heating) 12.2 9.2 10.8 ppm/(° C.) T.sub.g onset (° C.) 505 T.sub.x onset (° C.) T.sub.x onset − T.sub.g onset (° C.) a Liquidus Internal (° C.) 900 1015 a. No crystallization peak in DSC.

TABLE-US-00013 TABLE 13 Mol % Component 113 114 115 116 B.sub.2O.sub.3 2.6 P.sub.2O.sub.5 25.7 30.2 31.2 30 Li.sub.2O 16.5 Na.sub.2O 16.5 20.9 13.9 24.7 K.sub.2O 7.0 R.sub.2O (Li.sub.2O + Na.sub.2O + K.sub.2O) 40.0 20.9 13.9 24.7 CaO BaO 4.7 9.6 SrO ZnO 3.5 9.6 19.5 RO 4.7 9.6 RO + ZnO(MgO + CaO + 3.5 14.3 29.1 BaO + SrO + ZnO) R.sub.2O + RO + ZnO 43.5 35.2 43.0 24.7 TiO.sub.2 9.6 10 Nb.sub.2O.sub.5 17.6 24.1 25.1 35.3 WO.sub.3 10.0 Nb.sub.2O.sub.5 + TiO.sub.2 + WO.sub.3 27.6 33.7 25.1 45.3 CeO.sub.2 0.8 0.8 Ta.sub.2O.sub.5 0.6 Properties Density (g/ccm.sup.3) 3.509 3.523 nD 1.755 1.848 1.818 1.904 V.sub.d 21.88 25.30 20.86 Strain Point 558 531 622.9 Annealing Point 594 566 655.8 Softening point 720 763 T.sub.gonset (° C.) 454 669 T.sub.xonset (° C.) (ExPC 1 onset ° C.) 841 T.sub.xonset − T.sub.gonset a 172 a No crystallization peak in DSC.

Example 3: Glass Compositions with Refractive Index Greater Than 1.8

[0094] Glass compositions as disclosed herein having refractive index higher than 1.8 are presented in Tables 14 through 21 along with selected properties. Abbreviations representing properties not already listed in Example 2 are reviewed below:

TABLE-US-00014 TABLE 14 Component 117 118 119 120 121 Li.sub.2O 5 5 5 5 5 Na.sub.2O 5 5 5 5 5 K.sub.2O 5 5 5 5 5 CaO 12.5 11.25 10 9 7 BaO 12.5 11.25 10 9 7 ZnO 10 10 10 9.5 8.5 TiO.sub.2 2.5 Nb.sub.2O.sub.5 25 27.5 30 30 30 WO.sub.3 7.5 P.sub.2O.sub.5 25 25 25 25 25 Properties Density 3.86 3.85 3.835 3.977 (g/cm.sup.3) n532 1.869 1.879 1.892 1.906 1.921 nD 1.859 1.868 1.881 1.894 1.908 n633 1.850 1.86 1.872 1.885 1.899

TABLE-US-00015 TABLE 15 Component 122 123 124 125 126 127 128 129 130 Li.sub.2O 5 5 5 5 5 5 5 5 5 Na.sub.2O 5 5 5 5 5 5 5 5 5 K.sub.2O 5 5 5 5 5 5 5 5 5 CaO 9 9 9 9 9 9 8 8 12.5 BaO 9.5 9.5 9.5 9.5 9.5 9.5 9 9 12.5 ZnO 9 9 9 9 9 9 8 8 TiO.sub.2 5 7. 10 7.5 7.5 Nb.sub.2O.sub.5 27.5 25 22.5 27.5 25 22.5 25 25 25 WO.sub.3 5 7.5 10 7.5 P.sub.2O.sub.5 25 25 25 25 25 25 27.5 27.5 27.5 Properties Density (g/cm.sup.3) 3.825 3.794 3.76 3.946 3.979 3.993 3.719 3.902 3.721 n532 1.903 1.894 1.886 1.896 1.884 1.871 1.879 1.867 1.871 nD 1.89 1.882 1.874 1.884 1.872 1.86 1.868 1.856 1.859 n633 1.881 1.873 1.864 1.875 1.863 1.851 1.859 1.847 1.851 T.sub.g 590 586 582 578 567 559 587 570 609 T.sub.x 720 728 741 707 720 743 797 815 806 T.sub.x − T.sub.g 130 142 159 129 153 184 210 245 197 CTE(α)(10.sup.7/° C.) 83.5 Nanostrip (mg/cm.sup.2) 0.004 0.015 0.006 0.012

TABLE-US-00016 TABLE 16 Component 131 132 133 134 135 136 137 138 Li.sub.2O 5 5 5 5 5 5 5 5 Na.sub.2O 5 5 5 5 5 5 5 5 K.sub.2O 5 5 5 5 5 5 5 5 CaO 9 9 9 10 8 7.5 8 7.5 BaO 9.5 9.5 9.5 11 8 7.5 8 7.5 ZnO 9 9 9 11 9 7.5 9 7.5 TiO.sub.2 2.5 2.5 10 12.5 12.5 15 Nb.sub.2O.sub.5 32.5 30 30.5 25 25 25 22.5 22.5 WO.sub.3 2 2.5 P.sub.2O.sub.5 25 25 25 23 25 25 25 25 Properties Density (g/cm.sup.2) 3.881 3.851 3.908 3.946 3.767 3.748 3.736 3.711 n519 1.922 1.914 1.913 1.892 1.911 1.922 1.902 1.913 nD 1.906 1.898 1.897 1.877 1.895 1.906 1.886 1.897 n633 1.896 1.889 1.888 1.868 1.885 1.895 1.876 1.887 T.sub.g 596 586 581 589 577 584 T.sub.x 700 703 717 724 726 735 T.sub.x − T.sub.g 104 117 136 135 149 151 a (10.sup.−7/° C.) 80.3 83.2 78.4 80 83 Nanostrip (mg/cm.sup.2) 0.004 0.023 0.03 0.028 0.006

TABLE-US-00017 TABLE 17 Component 139 140 141 142 143 144 145 146 Li.sub.2O 5 5 5 5 5 5 5 5 Na.sub.2O 5 5 5 5 5 5 5 5 K.sub.2O 5 5 5 5 5 5 5 5 MgO 5.5 4 4 CaO 8 7.5 5 4 4 6.5 6 5 BaO 8 7.5 8 8 8 6.5 5.5 5 ZnO 9 7.5 9 9 9 7 6 6 TiO.sub.2 5 10 12.5 20 25 29 Nb.sub.2O.sub.5 25 25 27.5 25 22.5 20 17.5 15 WO.sub.5 10 12.5 P.sub.2O.sub.5 25 25 25 25 25 25 25 25 Properties Density (g/cm.sup.3) 4.018 4.06 3.777 3.742 3.646 3.583 3.536 n519 1.895 1.904 1.912 1.903 n532 1.909 1.913 1.912 nD 1.88 1.888 1.897 1.888 1.896 1.899 1.899 n633 1.871 1.879 1.887 1.878 1.887 1.889 1.889 T.sub.g 579 574 585 590 593 T.sub.x 689 699 772 781 815 T.sub.x − T.sub.g 110 125 187 191 221 a (10.sup.−7/° C.) 81.4 81.2 83.8 80.3 Nanostrip (mg/cm.sup.2) 0.012 0.037

TABLE-US-00018 TABLE 18 Component 147 148 149 150 151 152 153 154 Li.sub.2O 5 5 5 5 5 5 5 5 Na.sub.2O 5 5 5 5 5 5 5 5 K.sub.2O 5 5 5 5 5 5 5 5 CaO 4.14 8 7.5 7 6.5 6 5.5 7.5 BaO 4 7.5 7 7 6 6 5.5 7 ZnO 5 9 7.5 7.5 7 7 6 7.5 TiO.sub.2 11.25 10 15 15 20 20 20 10 SnO.sub.2 0.5 0.5 1 0.5 1 Nb.sub.2O.sub.5 35.75 25 22.5 22.5 20 20 21 26 Al.sub.2O.sub.3 2 2 P.sub.2O.sub.5 24.86 25 25 25 25 25 25 25 Properties Density (g/cm.sup.3) 3.785 3.769 3.714 3.722 3.654 3.663 3.614 3.731 n519 1.915 1.911 n532 1.986 1.907 1.909 1.909 1.912 1.913 nD 1.971 1.893 1.896 1.896 1.898 1.899 1.899 1.895 n633 1.959 1.885 1.887 1.887 1.889 1.89 1.888 1.885 T.sub.g 585 582 T.sub.x 699 693 T.sub.x − T.sub.g 114 111 Nanostrip (mg/cm.sup.2) 0.007 0.004

TABLE-US-00019 TABLE 19 Component 155 156 157 158 159 160 161 162 163 Li.sub.2O 7 5 5 5 5 5 5 Na.sub.2O 8 8 15 5 5 5 5 5 5 K.sub.2O 7 5 5 5 5 5 5 CaO 8 8 8 24 11 11 SrO 13 18 13 BaO 8 8 8 24 29 11 ZnO 8 8 8 TiO.sub.2 10 10 10 10 10 10 10 Nb.sub.2O.sub.5 26 26 26 26 26 31 26 31 26 P.sub.2O.sub.5 25 25 25 25 25 25 25 25 25 Properties Density (g/cm.sup.3) 3.797 3.746 3.779 3.557 3.979 4.097 3.687 3.792 3.874 n519 1.928 1.901 1.91 1.91 1.899 1.889 1.906 1.894 1.899 nD 1.911 1.885 1.894 1.894 1.884 1.875 1.89 1.879 1.884 n633 1.901 1.876 1.884 1.884 1.874 1.866 1.88 1.87 1.874 T.sub.g 620 628 614 617 T.sub.x 723 811 747 804 T.sub.x − T.sub.g 103 183 133 187 Nanostrip (mg/cm.sup.2) <0.001 0.014 0.044

TABLE-US-00020 TABLE 20 Component 164 165 166 167 168 169 170 171 172 Li.sub.2O 6.6 6.6 6.6 5 5 5 3.3 3.3 3.3 Na.sub.2O 6.8 6.8 6.8 5 5 5 3.4 3.4 3.4 K.sub.2O 6.6 6.6 6.6 5 5 5 3.3 3.3 3.3 CaO 5 7 8 7 8 10 8 10 12 SrO 4.5 6 8 6 8 9.5 8 9.5 11 BaO 4.5 6 8 6 8 9.5 8 9.5 11 TiO.sub.2 20 10 20 10 20 10 Nb.sub.2O.sub.5 21 26 31 21 26 31 21 26 31 P.sub.2O.sub.5 25 25 25 25 25 25 25 25 25 Properties Density 3.585 3.694 3.795 3.663 3.781 3.876 3.759 3.857 3.948 (g/cm.sup.3) n532 1.903 1.893 1.882 1.912 1.901 1.89 1.922 1.909 1.898 nD 1.89 1.881 1.871 1.899 1.889 1.879 1.909 1.897 1.887 n633 1.88 1.872 1.862 1.89 1.88 1.87 1.899 1.888 1.878 T.sub.g 607 604 602 625 623 622 638 637 633 T.sub.x 769 758 730 787 787 751 815 811 770 T.sub.x-T.sub.g 162 155 127 162 165 130 177 175 137

TABLE-US-00021 TABLE 21 Component 173 174 175 176 177 Li.sub.2O 5 5 5 5 5 Na.sub.2O 5 5 5 5 5 K.sub.2O 5 5 5 5 5 CaO 5 5 7 5 8 SrO 3 5 BaO 4 5 6 5 7 ZnO 4 TiO.sub.2 15 15 15 10 10 Nb.sub.2O.sub.5 32 32 32 35 35 P.sub.2O.sub.5 25 25 25 25 25 Properties Density (g/cm.sup.3) 3.747 3.766 3.759 3.823 3.825 n532 1.99 1.981 1.981 1.98 1.985 nD 1.974 1.966 1.966 1.965 1.97 n633 1.962 1.954 1.954 1.954 1.958 Nanostrip (mg/cm.sup.2) 0.012 0.014 0.013 0.006

[0095] Glass compositions as disclosed herein having refractive index higher than 1.8 are presented in Tables 22 through 25 along with selected properties. Abbreviations representing properties not already listed previously herein are reviewed below:

TABLE-US-00022 TABLE 22 Composition 178 179 180 181 182 183 184 188 188 187 188 Mol % Batched P.sub.2O.sub.5 30 30 30 27.5 25 25 25 30 30 30 30 Na.sub.2O 25 15 25 15 5 5 BaO 10 5 10 12.5 17.5 10 12.5 12.5 SrO 32.5 5 10 12.5 17.5 10 12.5 12.5 ZnO 5 5 5 10 TiO.sub.2 10 25 10 15 10 10 10 10 10 Nb.sub.2O.sub.5 35 20 30 20 35 35 35 35 30 30 30 WO.sub.3 5 5 5 5 5 Compositional Reduced P.sub.2O5 30 30 30 28 25 25 25 30 30 30 30 R.sub.2O 25 15 25 0 15 5 0 0 5 0 0 RO 0 10 0 33 10 20 25 35 20 25 25 ZnO 0 0 0 0 5 5 5 0 0 0 10 TiO.sub.2 10 25 10 15 10 10 10 0 10 10 0 Nb.sub.2O.sub.5 35 20 30 20 35 35 35 35 30 30 30 WO.sub.3 0 0 5 5 0 0 0 0 5 5 5 (R.sub.2O + RO)/ 0.83 0.83 0.83 1.18 1.00 1.00 1.00 1.17 0.83 0.83 0.83 P.sub.2O.sub.5 R.sub.2O + RO + 25 25 25 33 30 30 30 35 25 25 35 ZnO R.sub.2O/ 1 1 1 0 1 0 0 0 0 0 0 (R.sub.2O + RO) Properties Density 3.523 3.564 3.587 3.949 3.823 3.983 4.093 4.054 3.922 4.006 4.075 (g/cm.sup.3) nD 1.9039 1.9292 1.8600 1.8808 1.9572 1.9739 1.9783 1.8992 1.9228 1.9293 1.8921 V.sub.d 20.86 22.17 18.88 19.56 19.41 22.20 19.94 20.25 22.38 CTE 7.6 7.8 7.2 6.6 6.1 6.9 6.0 6.0 5.9 (<300° C., on heating) (ppm/° C.) Annealing 656 655 633 652 676 712 683 715 663 Point (13) (° C.) Strain Point 623 621 600 618 643 678 649 680 628 (14.5) (° C.) Softening Point 763 766 754 827 806 818 786 (7.6) (° C.) T.sub.g onset (° C.) 669 670 655 700 644 665 690 723 698 724 675 T.sub.x onset (° C.) 841 829 854 855 748 775 792 888 857 877 842 T.sub.x onset - T.sub.g 172 159 200 155 104 110 103 165 159 154 167 (° C.) Liquidus 1155 Internal (° C.) AO weight loss 2.00E−04 4.16E−05 (mg/mm.sup.2) Nanostrip <2E−06 8.32E−05 (mg/mm.sup.2) Poisson's Ratio 0.242 0.242 0.249 0.251 0.255 0.247 0.241 0.247 0.258 Shear Modulus 38.2 38.4 40.4 40.8 40.0 36.2 37.5 38.7 36.7 (GPa) Young's 94.9 95.4 100.9 102.0 100.3 90.5 93.1 96.4 92.2 Modulus (GPa)

TABLE-US-00023 TABLE 23 Composition 189 190 191 192 193 194 195 196 197 198 Mol % Batched P.sub.2O.sub.5 25 20 30 30 30 25 30 30 30 30 Li.sub.2O 5 5 Na.sub.2O 5 5 20 15 20 25 25 25 25 K.sub.2O 5 5 5 5 CaO 15 15 1 BaO 15 15 5 10 25 SrO 5 ZnO 10 10 TiO.sub.2 10 10 10 5 22 10 10 10 10 Nb.sub.2O.sub.5 20 25 25 30 35 22 35 35 35 35 WO.sub.3 5 CeO.sub.2 0.1 0.1 0.01 0.001 0.01 0.1 Compositional Reduced P.sub.2O.sub.5 25 20 30 30 30 25 30 30 30 30 R.sub.2O 15 15 20 15 25 5 25 25 25 25 RO 30 30 5 10 5 26 0 0 0 0 ZnO 0 0 10 10 0 0 0 0 0 0 TiO.sub.2 10 10 10 0 5 22 10 10 10 10 Nb.sub.2O.sub.5 20 25 25 30 35 22 35 35 35 35 WO.sub.3 0 0 0 5 0 0 0 0 0 0 (R.sub.2O + RO)/P.sub.2O.sub.5 1.80 2.25 0.83 0.83 1.00 1.24 0.83 0.83 0.83 0.83 R.sub.2O + RO + ZnO 45 45 35 35 R.sub.2O/(R.sub.2O + RO) 0 0 1 1 Properties Density (g/cm.sup.3) 3.803 3.879 3.512 3.885 3.54 3.957 3.515 3.523 3.483 3.522 nD 1.8797 1.8995 1.8612 1.8600 1.8664 1.9096 1.9051 1.9034 1.9037 1.9038 V.sub.d 23.77 22.75 22.00 21.20 21.19 Softening Point (° C.) 720 T.sub.g onset (° C.) 621 600 610 606 676 T.sub.x onset (° C.) 803 710 827 837 851 T.sub.x onset - T.sub.g onset (° C.) 181 110 216 231 176

TABLE-US-00024 TABLE 24 Composition 199 200 201 202 203 204 205 206 207 208 Mol % Batched P.sub.2O.sub.5 30 30 30 30 25 30 30 30 25 30 Na.sub.2O 15 15 15 15 25 25 15 25 25 K.sub.2O 25 BaO 10 10 10 10 SrO 10 TiO.sub.2 25 25 25 25 10 10 10 10 10 10 Nb.sub.2O.sub.5 20 20 20 20 35 35 35 35 35 35 WO.sub.3 5 5 CeO.sub.2 0.001 0.01 0.1 Compositional Reduced P.sub.2O.sub.5 30 30 30 30 25 30 30 30 25 30 R.sub.2O 15 15 15 15 25 25 25 15 25 25 RO 10 10 10 10 0 0 0 10 0 0 TiO.sub.2 25 25 25 25 10 10 10 10 10 10 Nb.sub.2O.sub.5 20 20 20 20 35 35 35 35 35 35 WO.sub.3 0 0 0 0 5 0 0 0 5 0 (R.sub.2O +RO)/P.sub.2O.sub.5 0.83 0.83 0.83 0.83 1.00 0.83 0.83 0.83 1.00 0.83 R.sub.2O + RO 25 25 25 25 25 25 25 25 25 25 R.sub.2O/(R.sub.2O + RO) 0.60 0.60 0.60 0.60 1 1 1 0.60 1 1 Properties Density (g/cm.sup.3) 3.55 3.55 3.549 3.55 3.726 3.533 3.442 3.678 3.748 nD 1.8828 1.8828 1.8823 1.8824 1.9476 1.9021 1.8614 1.9252 1.9470 1.9178 T.sub.g onset (° C.) 653 675 714 686 654 T.sub.x onset (° C.) 770 860 852 866 772 T.sub.x onset - T.sub.g onset (° C.) 117 184 138 181 117

TABLE-US-00025 TABLE 25 Composition 209 210 211 212 213 214 215 216 217 218 Mol % Batched P.sub.2O.sub.5 30 30 30 25 30 30 30 25 25 25 Na.sub.2O 15 10 10 7.64 18.25 20 20 20 K.sub.2O 5 5 25 17.36 6.75 CaO 5 BaO 10 10 5 12.5 20 20 20 SrO 5 12.5 TiO.sub.2 25 25 25 10 10 10 10 Nb.sub.2O.sub.5 20 20 20 35 35 35 35 35 35 35 Compositional Reduced P.sub.2O.sub.5 30 30 30 25 30 30 30 25 25 25 R.sub.2O 15 15 15 0 25 25 25 20 20 20 RO 10 10 10 30 0 0 0 20 20 20 TiO.sub.2 25 25 25 10 10 10 10 0 0 0 Nb.sub.2O.sub.5 20 20 20 35 35 35 35 35 35 35 (R.sub.2O + RO)/P.sub.2O.sub.5 0.83 0.83 0.83 1.20 0.83 0.83 0.83 1.60 1.60 1.60 R.sub.2O + RO 25 25 25 30 25 25 25 40 40 40 R20/(R20+30RO) 0.60 0.60 0.60 0 1 1 1 0.50 0.50 0.50 Properties Density (g/cm.sup.3) 3.611 3.535 4.046 nD 1.8896 1.9172 1.9099 1.9846 1.8600 1.8800 1.9000 1.8886 1.8888 1.8896

Example 4: Controlling the Color of the Glass

[0096] A couple of different approaches were examined to control the color of the glass compositions.

[0097] In one experiment, glass composition 116 (Table 13) was heated at 660° C. with oxygen purge for 0.5 hour and 1 hour (FIG. 1A) and in air at 640° C. for 1 hour (FIG. 1B). Heat-treatment under both conditions bleached the color of the glass and improved the transmittance in the range of 350-500 μm as shown in FIGS. 1A and 1B.

[0098] In another experiment, glass composition 4 (Table 1) was heated at 660° C. with oxygen purge for 16 hours. As shown in FIG. 2, the glass composition that was heated under oxygen increased the refractive index of the glass compared to the same glass that was not heated under oxygen.

[0099] In another experiment, the addition of CeO.sub.2 was added to several glass compositions produced herein in order to modify the color of the glass (Table 26). Glass composition 4 did not include CeO.sub.2 and was used as the control. Glass compositions 118-120 contained from 0.01-1 mol % mol % CeO.sub.2. The glass compositions prepared with CeO.sub.2 in general had a higher refractive index (FIG. 3A) and percent transmittance (FIG. 3B) compared to glass composition 4.

TABLE-US-00026 TABLE 26 Base glass Base glass with CeO.sub.2 addition (without CeO.sub.2) (0.001-1 mol %) 4 117 (0.001% CeO.sub.2), 118 (0.01% CeO.sub.2), 119 (0.1% CeO.sub.2), 120 (0.8% CeO.sub.2) 3 121 (0.8% CeO.sub.2) 45 122 (0.02% CeO.sub.2), 123 (0.2% CeO.sub.2) 87 124 (0.02% CeO.sub.2), 125 (0.2% CeO.sub.2) 94 126 (0.2% CeO.sub.2), 127 (0.02% CeO.sub.2)

[0100] Clause 1 of the present disclosure extends to:

A glass composition comprising: [0101] (a) P.sub.2O.sub.5 in an amount of 15 mol % to 40 mol %; [0102] (b) Nb.sub.2O.sub.5 is in an amount of 10 mol % to 50 mol %; and one of the following: [0103] (i) an alkali metal oxide (R.sub.2O) in an amount of 1 mol % to 35 mol %; at least two alkaline earth metal oxides (RO) in a combined amount of 5 mol % to 40 mol %, and [0104] wherein the glass composition does not include ZnO and B.sub.2O.sub.3; [0105] (ii) at least one alkali metal oxide (R.sub.2O) in an amount of 5 mol % to 35 mol %; and [0106] wherein the glass composition does not include ZnO, B.sub.2O.sub.3, or an alkaline earth metal oxide (RO); or [0107] (iii) at least one alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %; and [0108] wherein the glass composition does not include ZnO, B.sub.2O.sub.3, or an alkali metal oxide (R.sub.2O).

[0109] Clause 2 of the present disclosure extends to:

The glass composition of clause 1, wherein the composition comprises [0110] an alkali metal oxide (R.sub.2O) in an amount of 5 mol % to 35 mol %; [0111] at least two alkaline earth metal oxides (RO) in a combined amount of 5 mol % to 40 mol %, and [0112] wherein the glass composition does not include ZnO and B.sub.2O.sub.3.

[0113] Clause 3 of the present disclosure extends to:

The glass composition of clauses 1 or 2, wherein the molar ratio of (R.sub.2O+RO)/P.sub.2O.sub.5 is greater than or equal to 1.

[0114] Clause 4 of the present disclosure extends to:

The glass composition of clauses 1 or 2, wherein the molar ratio of (R.sub.2O+RO)/P.sub.2O.sub.5 is less than or equal to 1.

[0115] Clause 5 of the present disclosure extends to:

[0116] The glass composition of clauses 1 or 2, wherein the molar ratio of R.sub.2O/(R.sub.2O+RO) is greater than 0.25.

[0117] Clause 6 of the present disclosure extends to:

The glass composition of any of clauses 1-5, wherein P.sub.2O.sub.5 is in the amount of 15 mol % to 30 mol %.

[0118] Clause 7 of the present disclosure extends to:

The glass composition of any of clauses 1-6, wherein Nb.sub.2O.sub.5 is in the amount of 15 mol % to 30 mol %.

[0119] Clause 8 of the present disclosure extends to:

The glass composition of any of clauses 1-7, wherein P.sub.2O.sub.5 is in the amount of 20 mol % to 30 mol %.

[0120] Clause 9 of the present disclosure extends to:

The glass composition of any of clauses 1-8, wherein Nb.sub.2O.sub.5 is in the amount of 20 mol % to 30 mol %.

[0121] Clause 10 of the present disclosure extends to:

The glass composition of any of clauses 1-9, wherein R.sub.2O is Na.sub.2O, Li.sub.2O, K.sub.2O, or any combination thereof.

[0122] Clause 11 of the present disclosure extends to:

The glass composition of any of clauses 1-10, wherein R.sub.2O comprises Na.sub.2O in the amount of 1 mol % to 35 mol %.

[0123] Clause 12 of the present disclosure extends to:

The glass composition of any of clauses 1-11, wherein R.sub.2O comprises Li.sub.2O in the amount of 1 mol % to 15 mol %.

[0124] Clause 13 of the present disclosure extends to:

The glass composition of any of clauses 1-12, wherein R.sub.2O comprises K.sub.2O in the amount of 1 mol % to 10 mol %.

[0125] Clause 14 of the present disclosure extends to:

The glass composition of any of clauses 1-13, wherein R.sub.2O comprises Na.sub.2O in the amount of 1 mol % to 15 mol %, Li.sub.2O in the amount of 1 mol % to 15 mol %, K.sub.2O in the amount of 1 mol % to 10 mol %, or any combination thereof.

[0126] Clause 15 of the present disclosure extends to:

The glass composition of any of clauses 1-14, wherein RO comprises BaO in the amount of 1 mol % to 25 mol % and CaO in the amount of 1 mol % to 25 mol %.

[0127] Clause 16 of the present disclosure extends to:

The glass composition of any of clauses 1-15, wherein RO comprises BaO in the amount of 1 mol % to 25 mol % and MgO in the amount of 1 mol % to 25 mol %.

[0128] Clause 17 of the present disclosure extends to:

The glass composition of any of clauses 1-16, wherein RO comprises BaO in the amount of 1 mol % to 25 mol %, CaO in the amount of 1 mol % to 25 mol %, SrO in the amount of 1 mol % to 25 mol %, or any combination thereof.

[0129] Clause 18 of the present disclosure extends to:

The glass composition of any of clauses 1-17, wherein R.sub.2O comprises Na.sub.2O in the amount of 1 mol % to 15 mol %, Li.sub.2O in the amount of 1 mol % to 15 mol %, and K.sub.2O in the amount of 1 mol % to 10 mol %, and RO comprises BaO in the amount of 1 mol % to 25 mol %, CaO in the amount of 1 mol % to 25 mol %, and SrO in the amount of 1 mol % to 25 mol %.

[0130] Clause 19 of the present disclosure extends to:

The glass composition of any of clauses 1-18, wherein the composition further comprises TiO.sub.2 and/or WO.sub.3, wherein the amount of Nb.sub.2O.sub.5 an amount of TiO.sub.2 and/or an amount of WO.sub.3, or any combination thereof, sums to 20 mol % to 50 mol %.

[0131] Clause 20 of the present disclosure extends to:

The glass composition of any of clauses 1-19, wherein the composition further comprises TiO.sub.2 in an amount of 1 mol % to 30 mol %.

[0132] Clause 21 of the present disclosure extends to:

The glass composition of any of clauses 1-20, wherein the composition further comprises WO.sub.3 in an amount of 1 mol % to 15 mol %.

[0133] Clause 22 of the present disclosure extends to:

The glass composition of any of clauses 1-21, wherein the composition further comprises Al.sub.2O.sub.3 in an amount of 1 mol % to 5 mol %.

[0134] Clause 23 of the present disclosure extends to:

The glass composition of any of clauses 1-22, wherein the composition further comprises CeO.sub.2 in an amount of 0.001 mol % to 1.0 mol %.

[0135] Clause 24 of the present disclosure extends to:

The glass composition of any of clauses 1-23, wherein the glass composition does not include SiO.sub.2, Al.sub.2O.sub.3, MgO, TiO.sub.2, or any combination thereof.

[0136] Clause 25 of the present disclosure extends to:

The glass composition of any of clauses 1-24, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 15 mol % to 25 mol % and TiO.sub.2 in the amount of 15 mol % to 25 mol %.

[0137] Clause 26 of the present disclosure extends to:

The glass composition of any of clauses 1-25, wherein the sum of Nb.sub.2O.sub.5 and TiO.sub.2 is 40 mol % to 50 mol %.

[0138] Clause 27 of the present disclosure extends to:

The glass composition of any of clauses 1-26, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 15 mol % to 25 mol %, TiO.sub.2 in the amount of 15 mol % to 25 mol %, and P.sub.2O.sub.5 in an amount of 20 mol % to 30 mol %.

[0139] Clause 28 of the present disclosure extends to:

The glass composition of any of clauses 1-27, wherein the sum of Nb.sub.2O.sub.5 and TiO.sub.2 is 40 mol % to 50 mol %.

[0140] Clause 29 of the present disclosure extends to:

The glass composition of clause 1, wherein the composition comprises [0141] at least one alkali metal oxide (R.sub.2O) in an amount of 5 mol % to 35 mol %; and wherein the glass composition does not include ZnO, B.sub.2O.sub.3, or an alkaline earth metal oxide (RO).

[0142] Clause 30 of the present disclosure extends to:

The glass composition of clause 29, wherein the molar ratio of R.sub.2O/P.sub.2O.sub.5 is greater than or equal to 1.

[0143] Clause 31 of the present disclosure extends to:

The glass composition of clause 29, wherein the molar ratio of R.sub.2O/P.sub.2O.sub.5 is less than or equal to 1.

[0144] Clause 32 of the present disclosure extends to:

The glass composition of any of clauses 29-31, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 30 mol % to 40 mol % and TiO.sub.2 in the amount of 5 mol % to 15 mol %.

[0145] Clause 33 of the present disclosure extends to:

The glass composition of any of clauses 29-32, wherein the sum of Nb.sub.2O.sub.5 and TiO.sub.2 is 40 mol % to 50 mol %.

[0146] Clause 34 of the present disclosure extends to:

The glass composition of any of clauses 29-33, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 30 mol % to 40 mol % and TiO.sub.2 in the amount of 5 mol % to 15 mol %, and P.sub.2O.sub.5 in an amount of 20 mol % to 30 mol %.

[0147] Clause 35 of the present disclosure extends to:

The glass composition of any of clauses 29-34, wherein the sum of Nb.sub.2O.sub.5 and TiO.sub.2 is 40 mol % to 50 mol %.

[0148] Clause 36 of the present disclosure extends to:

The glass composition of any of clauses 29-35, wherein R.sub.2O is Na.sub.2O, Li.sub.2O, K.sub.2O, or any combination thereof.

[0149] Clause 37 of the present disclosure extends to:

The glass composition of any of clauses 29-36, wherein R.sub.2O comprises Na.sub.2O in the amount of 5 mol % to 40 mol %, Li.sub.2O in the amount of 5 mol % to 40 mol %, K.sub.2O in the amount of 5 mol % to 40 mol %, or any combination thereof.

[0150] Clause 38 of the present disclosure extends to:

The glass composition of any of clauses 29-37, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 30 mol % to 40 mol % and TiO.sub.2 in the amount of 5 mol % to 15 mol %, P.sub.2O.sub.5 in an amount of 20 mol % to 30 mol %, and R.sub.2O comprises Na.sub.2O in the amount of 5 mol % to 40 mol %, Li.sub.2O in the amount of 5 mol % to 40 mol %, K.sub.2O in the amount of 5 mol % to 40 mol %, or any combination thereof.

[0151] Clause 39 of the present disclosure extends to:

The glass composition of any of clauses 29-38, wherein the composition further comprises WO.sub.3 in an amount of 1 mol % to 15 mol %.

[0152] Clause 40 of the present disclosure extends to:

The glass composition of clause 1, wherein the composition comprises [0153] at least one alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %, [0154] wherein the glass composition does not include ZnO, B.sub.2O.sub.3, or an alkali metal oxide (R.sub.2O).

[0155] Clause 41 of the present disclosure extends to:

The glass composition of clause 40, wherein the molar ratio of RO/P.sub.2O.sub.5 is greater than or equal to 1.

[0156] Clause 42 of the present disclosure extends to:

The glass composition of clause 40, wherein the molar ratio of RO/P.sub.2O.sub.5 is less than or equal to 1.

[0157] Clause 43 of the present disclosure extends to:

The glass composition of any of clauses 40-42, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 30 mol % to 40 mol % and TiO.sub.2 in the amount of 5 mol % to 15 mol %.

[0158] Clause 44 of the present disclosure extends to:

The glass composition of any of clauses 40-43, wherein the sum of Nb.sub.2O.sub.5 and TiO.sub.2 is 40 mol % to 50 mol %.

[0159] Clause 45 of the present disclosure extends to:

The glass composition of any of clauses 40-44, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 30 mol % to 40 mol %, TiO.sub.2 in the amount of 5 mol % to 15 mol %, and P.sub.2O.sub.5 in an amount of 20 mol % to 30 mol %.

[0160] Clause 46 of the present disclosure extends to:

The glass composition of any of clauses 40-45, wherein the sum of Nb.sub.2O.sub.5 and TiO.sub.2 is 40 mol % to 50 mol %.

[0161] Clause 47 of the present disclosure extends to:

The glass composition of any of clauses 40-46, wherein RO comprises BaO, CaO, SrO or any combination thereof.

[0162] Clause 48 of the present disclosure extends to:

The glass composition of any of clauses 40-47, wherein RO comprises BaO in the amount of 1 mol % to 25 mol %, CaO in the amount of 1 mol % to 25 mol %, SrO in the amount of 1 mol % to 25 mol %, or any combination thereof.

[0163] Clause 49 of the present disclosure extends to:

The glass composition of any of clauses 40-48, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 30 mol % to 40 mol %, TiO.sub.2 in the amount of 5 mol % to 15 mol %, P.sub.2O.sub.5 in an amount of 20 mol % to 30 mol %, BaO in the amount of 5 mol % to 20 mol %, CaO in the amount of 1 mol % to 10 mol %, and SrO in the amount of 5 mol % to 20 mol %.

[0164] Clause 50 of the present disclosure extends to:

A glass composition comprising: [0165] P.sub.2O.sub.5 in an amount of 20 mol % to 40 mol %; [0166] Nb.sub.2O.sub.5 in an amount of 10 mol % to 50 mol %; [0167] ZnO in an amount of 0.5 mol % to 20 mol %; and one of the following: [0168] (i) an alkali metal oxide (R.sub.2O) in an amount of 1 mol % to 35 mol %; an alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %, [0169] wherein the glass composition does not include B.sub.2O.sub.3; [0170] (ii) at least one alkali metal oxide (R.sub.2O) in an amount of 5 mol % to 35 mol %; [0171] wherein the glass composition does not include B.sub.2O.sub.3 or an alkaline earth metal oxide (RO); or [0172] (iii) at least one alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %; [0173] wherein the glass composition does not include B.sub.2O.sub.3 or an alkali metal oxide (R.sub.2O).

[0174] Clause 51 of the present disclosure extends to:

The glass composition of clause 50, wherein the composition comprises an alkali metal oxide (R.sub.2O) in an amount of 10 mol % to 35 mol %;

[0175] an alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %, and wherein the glass composition does not include B.sub.2O.sub.3.

[0176] Clause 52 of the present disclosure extends to:

The glass composition of clauses 50 or 51, wherein the amount of RO, the amount of R.sub.2O, and the amount of ZnO sum to 30 mol % to 60 mol %.

[0177] Clause 53 of the present disclosure extends to:

The glass composition of clauses 50 or 51, wherein the molar ratio of (R.sub.2O+RO)/P.sub.2O.sub.5 is greater than or equal to 1.

[0178] Clause 54 of the present disclosure extends to:

The glass composition of clauses 50 or 51, wherein the molar ratio of (R.sub.2O+RO)/P.sub.2O.sub.5 is less than or equal to 1.

[0179] Clause 55 of the present disclosure extends to:

The glass composition of clauses 50 or 51, wherein the molar ratio of R.sub.2O/(R.sub.2O+RO) is greater than 0.25.

[0180] Clause 56 of the present disclosure extends to:

The glass composition of any of clauses 51-55, wherein P.sub.2O.sub.5 is in the amount of 25 mol % to 35 mol %.

[0181] Clause 57 of the present disclosure extends to:

The glass composition of any of clauses 51-56, wherein Nb.sub.2O.sub.5 is in the amount of 15 mol % to 30 mol %.

[0182] Clause 58 of the present disclosure extends to:

The glass composition of any of clauses 51-57, wherein R.sub.2O is Na.sub.2O, Li.sub.2O, K.sub.2O, or any combination thereof.

[0183] Clause 59 of the present disclosure extends to:

The glass composition of any of clauses 51-58, wherein R.sub.2O comprises Na.sub.2O in the amount of 1 mol % to 35 mol %.

[0184] Clause 60 of the present disclosure extends to:

The glass composition of any of clauses 51-59, wherein R.sub.2O comprises Li.sub.2O in the amount of 1 mol % to 15 mol %.

[0185] Clause 61 of the present disclosure extends to:

The glass composition of any of clauses 51-60, wherein R.sub.2O comprises K.sub.2O in the amount of 1 mol % to 10 mol %.

[0186] Clause 62 of the present disclosure extends to:

The glass composition of any of clauses 50-61, wherein R.sub.2O comprises Na.sub.2O in the amount of 1 mol % to 15 mol %, Li.sub.2O in the amount of 1 mol % to 15 mol %, and K.sub.2O in the amount of 1 mol % to 10 mol %.

[0187] Clause 63 of the present disclosure extends to:

The glass composition of any of clauses 51-62, wherein RO is CaO, BaO, MgO, SrO, or any combination thereof.

[0188] Clause 64 of the present disclosure extends to:

The glass composition of any of clauses 51-63, wherein RO comprises BaO in the amount of 1 mol % to 25 mol %.

[0189] Clause 65 of the present disclosure extends to:

The glass composition of any of clauses 51-64, wherein RO comprises CaO in the amount of 1 mol % to 20 mol %.

[0190] Clause 66 of the present disclosure extends to:

The glass composition of any of clauses 51-65, wherein RO comprises MgO in the amount of 1 mol % to 15 mol %.

[0191] Clause 67 of the present disclosure extends to:

The glass composition of any of clauses 51-66, wherein RO comprises SrO in the amount of 1 mol % to 30 mol %.

[0192] Clause 68 of the present disclosure extends to:

The glass composition of any of clauses 51-67, wherein RO comprises BaO in the amount of 1 mol % to 20 mol % and CaO in the amount of 1 mol % to 20 mol %.

[0193] Clause 69 of the present disclosure extends to:

The glass composition of any of clauses 51-68, wherein RO comprises BaO in the amount of 1 mol % to 20 mol %, CaO in the amount of 1 mol % to 20 mol %, and SrO in the amount of 1 mol % to 20 mol %.

[0194] Clause 70 of the present disclosure extends to:

The glass composition of any of clauses 51-69, wherein the composition further comprises TiO.sub.2 and/or WO.sub.3, wherein the amount of Nb.sub.2O.sub.5, an amount of TiO.sub.2 and/or an amount WO.sub.3, or any combination thereof, sums to 20 mol % to 40 mol %.

[0195] Clause 71 of the present disclosure extends to:

The glass composition of any of clauses 51-70, wherein the composition further comprises TiO.sub.2 in an amount of 1 mol % to 30 mol %.

[0196] Clause 72 of the present disclosure extends to:

The glass composition of any of clauses 51-71, wherein the composition further comprises WO.sub.3 in an amount of 1 mol % to 15 mol %.

[0197] Clause 73 of the present disclosure extends to:

The glass composition of any of clauses 51-72, wherein the composition further comprises Al.sub.2O.sub.3 in an amount of 1 mol % to 5 mol %.

[0198] Clause 74 of the present disclosure extends to:

The glass composition of any of clauses 51-73, wherein the composition further comprises CeO.sub.2 in an amount of 0.001 mol % to 1.0 mol %.

[0199] Clause 75 of the present disclosure extends to:

The glass composition of any of clauses 51-74, wherein the glass composition does not include any of SiO.sub.2, Al.sub.2O.sub.3, MgO, TiO.sub.2.

[0200] Clause 76 of the present disclosure extends to:

The glass composition of any of clauses 51-75, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 30 mol % to 40 mol %, TiO.sub.2 in the amount of 5 mol % to 15 mol %, P.sub.2O.sub.5 in an amount of 20 mol % to 35 mol %, ZnO in the amount of 1 mol % to 15 mol %, RO in the amount of 5 mol % to 40 mol %, where RO is BaO, CaO, SrO, or any combination thereof, and R.sub.2O in the amount of 1 mol % to 35 mol %, where R.sub.2O is Na.sub.2O, Li.sub.2O, K.sub.2O, or any combination thereof.

[0201] Clause 77 of the present disclosure extends to:

The glass composition of clause 50, wherein the composition comprises [0202] at least one alkali metal oxide (R.sub.2O) in an amount of 5 mol % to 35 mol %; [0203] wherein the glass composition does not include B.sub.2O.sub.3 or an alkaline earth metal oxide (RO).

[0204] Clause 78 of the present disclosure extends to:

The glass composition of clause 77, wherein P.sub.2O.sub.5 is in the amount of 25 mol % to 35 mol %.

[0205] Clause 79 of the present disclosure extends to:

The glass composition of clauses 77 or 78, wherein Nb.sub.2O.sub.5 is in the amount of 15 mol % to 30 mol %.

[0206] Clause 80 of the present disclosure extends to:

The glass composition of any of clauses 77-79, wherein R.sub.2O is Na.sub.2O, Li.sub.2O, K.sub.2O, or any combination thereof.

[0207] Clause 81 of the present disclosure extends to:

The glass composition of any of clauses 77-80, wherein R.sub.2O comprises Na.sub.2O in the amount of 1 mol % to 35 mol %.

[0208] Clause 82 of the present disclosure extends to:

The glass composition of any of clauses 77-81, wherein R.sub.2O comprises Li.sub.2O in the amount of 1 mol % to 15 mol %.

[0209] Clause 83 of the present disclosure extends to:

The glass composition of any of clauses 77-82, wherein R.sub.2O comprises K.sub.2O in the amount of 1 mol % to 10 mol %.

[0210] Clause 84 of the present disclosure extends to:

The glass composition of any of clauses 77-83, wherein the composition further comprises TiO.sub.2 in an amount of 1 mol % to 30 mol %.

[0211] Clause 85 of the present disclosure extends to:

The glass composition of any of clauses 77-84, wherein the composition further comprises WO.sub.3 in an amount of 1 mol % to 15 mol %.

[0212] Clause 86 of the present disclosure extends to:

The glass composition of any of clauses 77-85, wherein R.sub.2O comprises Na.sub.2O in the amount of 1 mol % to 15 mol %, Li.sub.2O in the amount of 1 mol % to 15 mol %, and K.sub.2O in the amount of 1 mol % to 10 mol %.

[0213] Clause 87 of the present disclosure extends to:

The glass composition of any of clauses 77-86, wherein the molar ratio of R.sub.2O to P.sub.2O.sub.5 is greater than or equal to 1.

[0214] Clause 88 of the present disclosure extends to:

The glass composition of any of clauses 77-87, wherein the molar ratio of R.sub.2O to P.sub.2O.sub.5 is less than or equal to 1.

[0215] Clause 89 of the present disclosure extends to:

The glass composition of any of clauses 77-88, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 30 mol % to 40 mol %, TiO.sub.2 in the amount of 5 mol % to 15 mol %, P.sub.2O.sub.5 in an amount of 20 mol % to 35 mol %, ZnO in the amount of 1 mol % to 15 mol %, and R.sub.2O in the amount of 1 mol % to 35 mol %, where R.sub.2O is Na.sub.2O, Li.sub.2O, K.sub.2O, or any combination thereof.

[0216] Clause 90 of the present disclosure extends to:

The glass composition of clause 50, wherein the composition comprises [0217] at least one alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %; and [0218] wherein the glass composition does not include B.sub.2O.sub.3 or an alkali metal oxide (R.sub.2O).

[0219] Clause 91 of the present disclosure extends to:

The glass composition of clause 90, wherein P.sub.2O.sub.5 is in the amount of 25 mol % to 35 mol %.

[0220] Clause 92 of the present disclosure extends to:

The glass composition of clauses 90 or 91, wherein Nb.sub.2O.sub.5 is in the amount of 15 mol % to 30 mol %.

[0221] Clause 93 of the present disclosure extends to:

The glass composition of any of clauses 90-92, wherein RO is CaO, BaO, MgO, SrO, or any combination thereof.

[0222] Clause 94 of the present disclosure extends to:

The glass composition of any of clauses 90-93, wherein RO comprises BaO in the amount of 1 mol % to 25 mol %.

[0223] Clause 95 of the present disclosure extends to:

The glass composition of any of clauses 90-94, wherein RO comprises CaO in the amount of 1 mol % to 20 mol %.

[0224] Clause 96 of the present disclosure extends to:

The glass composition of any of clauses 90-95, wherein RO comprises MgO in the amount of 1 mol % to 15 mol %.

[0225] Clause 97 of the present disclosure extends to:

The glass composition of any of clauses 90-96, wherein RO comprises SrO in the amount of 1 mol % to 30 mol %.

[0226] Clause 98 of the present disclosure extends to:

The glass composition of any of clauses 90-97, wherein RO comprises BaO in the amount of 1 mol % to 20 mol % and CaO in the amount of 1 mol % to 20 mol %.

[0227] Clause 99 of the present disclosure extends to:

The glass composition of any of clauses 90-98, wherein RO comprises BaO in the amount of 1 mol % to 20 mol %, CaO in the amount of 1 mol % to 20 mol %, and SrO in the amount of 1 mol % to 20 mol %.

[0228] Clause 100 of the present disclosure extends to:

The glass composition of any of clauses 90-99, wherein the composition further comprises TiO.sub.2 in an amount of 1 mol % to 30 mol %.

[0229] Clause 101 of the present disclosure extends to:

The glass composition of any of clauses 90-100, wherein the composition further comprises WO.sub.3 in an amount of 1 mol % to 15 mol %.

[0230] Clause 102 of the present disclosure extends to:

The glass composition of any of clauses 90-101, wherein the molar ratio of RO to P.sub.2O.sub.5 is greater than or equal to 1.

[0231] Clause 103 of the present disclosure extends to:

The glass composition of any of clauses 90-101, wherein the molar ratio of RO to P.sub.2O.sub.5 is less than or equal to 1.

[0232] Clause 104 of the present disclosure extends to:

The glass composition of any of clauses 90-103, wherein the glass composition comprises Nb.sub.2O.sub.5 in the amount of 30 mol % to 40 mol %, TiO.sub.2 in the amount of 5 mol % to 15 mol %, P.sub.2O.sub.5 in an amount of 20 mol % to 35 mol %, ZnO in the amount of 1 mol % to 15 mol %, and RO in the amount of 5 mol % to 40 mol %, where RO is BaO, CaO, SrO, or any combination thereof.

[0233] Clause 105 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a glass thermal stability index of greater than or equal to 200° C.

[0234] Clause 106 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a glass thermal stability index of greater than or equal to 225° C.

[0235] Clause 107 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a glass thermal stability index of less than zero.

[0236] Clause 108 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a refractive index of at least 1.70 at 588 nm at 25° C.

[0237] Clause 109 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a refractive index of at least 1.75 at 588 nm at 25° C.

[0238] Clause 110 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a refractive index of 1.70 to 2.00 at 588 nm at 25° C.

[0239] Clause 111 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a density of less than or equal to 4 g/cm.sup.3.

[0240] Clause 112 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has an Abbe number of at least 20.

[0241] Clause 113 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has an Abbe number of from 20 to 40.

[0242] Clause 114 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a coefficient of thermal expansion of from 6.0 ppm/° C. to 12 ppm/° C.

[0243] Clause 115 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has an annealing point of 450° C. to 750° C.

[0244] Clause 116 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a softening point of 575° C. to 850° C.

[0245] Clause 117 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has an internal liquidus temperature of 875° C. to 1,200° C.

[0246] Clause 118 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition has a Young's modulus of 50 GPa to 110 GPa.

[0247] Clause 119 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glass composition is a glass sheet, powder, bead, fiber, or three-dimensional scaffold.

[0248] An optical article comprising the glass composition of any of clauses 1-104.

[0249] Throughout this publication, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the methods, compositions, and compounds herein.

[0250] Various modifications and variations can be made to the materials, methods, and articles described herein. Other aspects of the materials, methods, and articles described herein will be apparent from consideration of the specification and practice of the materials, methods, and articles disclosed herein. It is intended that the specification and examples be considered as exemplary.