Glass and glass ceramic compositions having a combination of lithium silicate and petalite crystalline phases along with methods of making the glass and glass ceramic compositions are described. The compositions are compatible with conventional rolling and float processes, are transparent or translucent, and have high mechanical strength and fracture resistance. Further, the compositions are able to be chemically tempered to even higher strength glass ceramics that are useful as large substrates in multiple applications.

Provided is a block body that makes it possible to quickly produce a dental prosthesis with a good accuracy. A material of the block body including SiO.sub.2 in an amount of 60.0 mass % to 80.0 mass %, Li.sub.2O in an amount of 10.0 mass % to 20.0 mass %, Al.sub.2O.sub.3 in an amount of 5.1 mass % to 10.0 mass %, wherein the block body is formed in a column, and a main crystalline phase of the block body is lithium disilicate.

Optically transparent glass ceramic materials comprising a glass phase containing and a crystalline tungsten bronze phase comprising nanoparticles and having the formula M.sub.xWO.sub.3, where M includes at least one H, Li, Na, K, Rb, Cs, Ca, Sr, Ba, Zn, Cu, Ag, Sn, Cd, In, Tl, Pb, Bi, Th, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, and U, and where 0<x<1. Aluminosilicate and zinc-bismuth-borate glasses comprising at least one of Sm.sub.2O.sub.3, Pr.sub.2O.sub.3, and Er.sub.2O.sub.3 are also provided.

Glass ceramics having SiO.sub.2 as main crystal phase and precursors thereof are described which are characterized by very good mechanical and optical properties and in particular can be used as restoration material in dentistry.

Manufacturing glass ceramic materials comprises ceramming a glass to grow a crystalline tungsten bronze phase comprising nanoparticles having a formula M.sub.xWO.sub.3, where M includes a dopant cation, and where 0<x<1.

To provide a glass article suitable for a top plate for a cooker, in which a color tone of a colored layer is not impaired. A glass article is characterized by including a Li.sub.2O—Al.sub.2O.sub.3—SiO.sub.2-based crystallized glass sheet having lightness L* of 70 or greater, chromaticity a* of within ±5, and chromaticity b* of within ±5 at a thickness of 3 mm, and a colored layer formed on a back surface of the glass sheet.

The present invention relates to a chemically strengthened glass having a thickness of t (unit: .Math.m) and a relative permittivity of 7.0 or less at 20° C. and a frequency of 10 GHz, in which a value of Z determined by the following formula is 0.65 or more, where S1 is an entropy function calculated from an amount of alkali ions in a center portion of the glass, S2 is an entropy function calculated from an average amount of alkali ions from a glass surface to a depth of 0.05t, and X (unit: MPa) is an average value of a compressive stress in a region from the glass surface to the depth of 0.05t: Z = (S2 - S1) × 10 + X/1000.

A glass composition includes: greater than or equal to 53 mol % and less than or equal to 70 mol % SiO.sub.2; greater than or equal to 9 mol % and less than or equal to 20 mol % Al.sub.2O.sub.3; greater than or equal to 10 mol % and less than or equal to 17.5 mol % B.sub.2O.sub.3; greater than or equal to 0 mol % Li.sub.2O; greater than or equal to 0 mol % Na.sub.2O; and greater than 0.1 mol % of a nucleating agent. The sum of Li.sub.2O and Na.sub.2O in the glass composition may be greater than or equal to 8 mol % and less than or equal to 30 mol %. The amount of Al.sub.2O.sub.3 minus the sum of R.sub.2O and RO in the glass composition may be greater than or equal to −3 mol %. The glass composition may be phase separable and may have an improved K.sub.Ic fracture toughness.

A black lithium silicate glass ceramic is provided. The glass ceramic includes lithium silicate as a primary crystal phase and at least one of petalite, β-quartz, β-spodumene, cristobalite, and lithium phosphate as a secondary crystal phase. The glass ceramic is characterized by the color coordinates: L*: 20.0 to 40.0, a*: −1.0 to 1.0, and b*: −5.0 to 2.0. The glass ceramic may be ion exchanged. Methods for producing the glass ceramic are also provided.

A glass substrate and a method for manufacturing the glass substrate are provided. The glass substrate may include a base glass including SiO.sub.2, Al.sub.2O.sub.3, and Li.sub.2O, and nanocrystals having an average diameter in a range from about 5 nm to about 10 nm, thereby exhibiting enhanced surface strength properties while maintaining good transmittance properties. The method may include a step of heat-treating a base glass, thereby providing a glass substrate having enhanced strength properties.