The present invention provides a glass sheet having soda-lime-silica glass composition with a high visible light transmittance (L.sub.tC) of at least 89% with a dominant wavelength (DW) from about 490 to 505 nanometers and purity (Pe) of no more than 1% for control thickness of 5.66 mm and methods of making the same. The glass composition comprising a low iron raw material, a total iron oxide (Fe.sub.2O.sub.3) of 0.02 to 0.06 wt. %, ferrous (FeO) from 0.006 to 0.02 wt. %, redox (FeO/Fe.sub.2O.sub.3) from about 0.30 to 0.55, Cr.sub.2O.sub.3 from about 0.3 to 10 ppm, TiO.sub.2 from about 50 to 500 ppm, SnO.sub.2 from about 10 to 500 ppm, and a critical amount from about 0.10 to 0.25 wt. % of SO.sub.3. The low content of iron oxide is achieved by the partial substitution of regular raw materials by low iron raw materials, with a complete substitution of regular dolomite by a low iron dolomite with a maximum content of 0.020 wt. % Fe.sub.2O.sub.3.

To provide a highly transmissive glass and a light guide that allow high internal transmittance of plate glass to be maintained and the internal transmittance spectrum of the plate to be flattened without lowering the redox of iron to a value equal to or more than a certain value. This glass article comprises a glass which includes 1 to 80 mass ppm of total iron oxide (t-Fe.sub.2O.sub.3) in terms of Fe.sub.2O.sub.3, has a redox of iron of 0 to 50% and includes 0.01 to 4.0 mass ppm of NiO. The glass article and the light guide comprising the glass article are characterized in that an A value of the internal transmittance spectrum flatness is 0.83 or more.

Embodiments of a transparent glass-based material comprising a glass phase and a second phase that is different from and is dispersed in the glass phase are provided. The second phase may comprise a crystalline or a nanocrystalline phase, a fiber, and/or glass particles. In some embodiments, the second phase is crystalline. In one or more embodiments, the glass-based material has a transmittance of at least about 88% over a visible spectrum ranging from about 400 nm to about 700 nm and a fracture toughness of at least about 0.9 MPa.Math.m.sup.1/2, and wherein a surface of the glass-based material, when scratched with a Knoop diamond at a load of at least 5 N to form a scratch having a width w, is free of chips having a size of greater than 3 w.

A glass has a basic soda-lime-silica glass portion, and a colorant portion including total iron as Fe.sub.2O.sub.3 selected from the group of total iron as Fe.sub.2O.sub.3 in the range of greater than zero to 0.02 weight percent; total iron as Fe.sub.2O.sub.3 in the range of greater than 0.02 weight percent to less than 0.10 weight percent and total iron as Fe.sub.2O.sub.3 in the range of 0.10 to 2.00 weight percent; redox ratio in the range of 0.2 to 0.8, and tin and/or fin compounds, e.g. SnO.sub.2 greater than 0.000 to 5.0 weight percent. In one embodiment of the invention, the glass has a fin side and an opposite air side, wherein the tin side of the glass is supported on a molten fin bath during forming of the glass. The tin concentration at the tin side of the glass is greater than, less than, or equal to the fin concentration hi “body portion” of the glass. The “body portion” of the glass extending from the air side of the glass toward the fin side and terminating short of the tin side of the glass.

Compounds, compositions, articles, devices, and methods for the manufacture of light guide plates and back light units including such light guide plates made from glass. In some embodiments, light guide plates (LGPs) are provided that have similar or superior optical properties to light guide plates made from PMMA and that have exceptional mechanical properties such as rigidity, CTE and dimensional stability in high moisture conditions as compared to PMMA light guide plates.

Compounds, compositions, articles, devices, and methods for the manufacture of light guide plates and back light units including such light guide plates made from glass. In some embodiments, light guide plates (LGPs) are provided that have similar or superior optical properties to light guide plates made from PMMA and that have exceptional mechanical properties such as rigidity, CTE and dimensional stability in high moisture conditions as compared to PMMA light guide plates.

A transparent gahnite-spinel glass ceramic is provided. The glass ceramic includes a first crystal phase including (Mg.sub.xZn.sub.1−x)Al.sub.2O.sub.4 where x is less than 1 and a second crystal phase including tetragonal ZrO.sub.2. The glass ceramic may be ion exchanged. Methods for producing the glass ceramic are also provided.

A glass-ceramic article includes 50 mol. % to 80 mol. % SiO.sub.2; 10 mol. % to 25 mol. % Al.sub.2O.sub.3; 5 mol. % to 20 mol. % MgO; 0 mol. % to 10 mol. % Li.sub.2O; and 1 mol. % to 3 mol. % of a nucleating agent. The nucleating agent is selected from the group consisting of ZrO.sub.2, TiO.sub.2, SnO.sub.2, HfO.sub.2, Ta.sub.2O.sub.5, Nb.sub.2O.sub.5, Y.sub.2O.sub.3, and combinations thereof. The nucleating agent may comprise greater than or equal to 50% ZrO.sub.2 and less than 50% of at least one compound selected from the group consisting of TiO.sub.2, SnO.sub.2, HfO.sub.2, Ta.sub.2O.sub.5, Nb.sub.2O.sub.5, Y.sub.2O.sub.3, and combinations thereof. The glass-ceramic article may have a molar ratio of MgO to Li.sub.2O of greater than or equal to 1:1. The glass-ceramic article may satisfy the relationship 0.85≤(MgO (mol %)+Li.sub.2O (mol %))/Al.sub.2O.sub.3 (mol %)≤1.2. The glass-ceramic article may comprise a crystalline phase comprising hexagonal stuffed β-quartz and glass.

Embodiments of a transparent glass-based material comprising a glass phase and a second phase that is different from and is dispersed in the glass phase are provided. The second phase may comprise a crystalline or a nanocrystalline phase, a fiber, and/or glass particles. In some embodiments, the second phase is crystalline. In one or more embodiments, the glass-based material has a transmittance of at least about 88% over a visible spectrum ranging from about 400 nm to about 700 nm and a fracture toughness of at least about 0.9 MPa.Math.m.sup.1/2, and wherein a surface of the glass-based material, when scratched with a Knoop diamond at a load of at least 5 N to form a scratch having a width w, is free of chips having a size of greater than 3w.

Embodiments of a transparent glass-based material comprising a glass phase and a second phase that is different from and is dispersed in the glass phase are provided. The second phase may comprise a crystalline or a nanocrystalline phase, a fiber, and/or glass particles. In some embodiments, the second phase is crystalline. In one or more embodiments, the glass-based material has a transmittance of at least about 88% over a visible spectrum ranging from about 400 nm to about 700 nm and a fracture toughness of at least about 0.9 MPa.Math.m.sup.1/2, and wherein a surface of the glass-based material, when scratched with a Knoop diamond at a load of at least 5 N to form a scratch having a width w, is free of chips having a size of greater than 3w.