Lithium silicate glass ceramics and precursors thereof are described, which comprise copper and are characterized by very good mechanical and optical properties and can be used in particular as restorative materials in dentistry.

Lithium silicate glass ceramics and precursors thereof are described, which contain tin and are characterized by very good mechanical and optical properties and can be used in particular as restorative materials in dentistry.

The present invention relates to a glass in which: the glass is a crystallized glass; the glass has a difference log η−log η.sub.0 (dPa.Math.s) between a logarithm log η (dPa.Math.s) of bulk viscosity η (dPa.Math.s) and a logarithm log η.sub.0 (dPa.Math.s) of local viscosity η.sub.0 (dPa.Math.s) of larger than 0 and 1.8 or smaller, in a temperature range in which the logarithm log η.sub.0 (dPa.Math.s) of the bulk viscosity η (dPa.Math.s) is 11.4 or larger and 12.7 or smaller.

The present disclosure relates to fusion formable highly crystalline glass-ceramic articles whose composition lies within the SiO.sub.2—R.sub.2O.sub.3—Li.sub.2O/Na.sub.2O—TiO.sub.2 system and which contain a silicate crystalline phase comprised of lithium aluminosilicate (β-spodumene and/or β-quartz solid solution) lithium metasilicate and/or lithium disilicate. Additionally, these silicate-crystal containing glass-ceramics can exhibit varying Na.sub.2O to Li.sub.2O molar ratio extending from the surface to the bulk of the glass article, particularly a decreasing Li.sub.2O concentration and an increasing Na.sub.2O concentration from surface to bulk. According to a second embodiment, disclosed herein is a method for forming a silicate crystalline phase-containing glass ceramic.

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.

The present invention relates to a chemically strengthened glass having a sheet shape, in which a haze in terms of a thickness of 0.70 mm is 1.0% or less, and on at least one main surface of the glass, a ratio (Rku/Hv)×1000 of kurtosis Rku of surface unevenness to Vickers hardness Hv is 1 or more and 4.4 or less.

The present invention relates to a chemically strengthened glass having a haze value in terms of a thickness of 0.7 mm of 0.5% or less, having a surface compressive stress value of 400 MPa or more, having a depth of a compressive stress layer of 70 μm or more, having an ST limit of 18000 MPa.Math.μm to 30000 MPa.Math.μm, and being a glass ceramic including at least one of a Li.sub.3PO.sub.4 crystal and a Li.sub.4SiO.sub.4 crystal, or including a solid solution crystal of Li.sub.3PO.sub.4 or Li.sub.4SiO.sub.4 or a solid solution of both Li.sub.3PO.sub.4 and Li.sub.4SiO.sub.4.

The present invention relates to a glass ceramic having a lithium aluminosilicate composition and including a crystal and a residual glass, in which the residual glass has a composition including, in terms of mol % based on oxides: 25% to 70% of SiO.sub.2; 3% to 35% of Al.sub.2O.sub.3; 0.1% to 20% of Li.sub.2O; 0.1% to 20% of Na.sub.2O; 0% to 10% of K.sub.2O; and 1% to 15% of ZrO.sub.2, and a parameter V is −600 or more and 720 or less, the parameter V being calculated based on the following formula: V=49.589×[SiO.sub.2]+61.806×[Al.sub.2O.sub.3]+45.456×[P.sub.2O.sub.5]+41.151×[MgO]+110.26×[CaO]+50.263×[SrO]+55.693×[Li.sub.2O]+3.598×[Na.sub.2O]+9.503×[K.sub.2O]+6.83×[TiO.sub.2]−2.885×[ZrO.sub.2]−3746.99.

A glass article includes a central layer including a first crystalline phase having a first coefficient of thermal expansion and a surface layer surrounding an entirety of the central layer and including a second crystalline phase having a second coefficient of thermal expansion smaller than the first coefficient of thermal expansion. Accordingly, the strength of the glass article may be improved.

A glass ceramic contains the following components by wt %: 60 to 80% of SiO.sub.2; 4 to 20% of Al.sub.2O.sub.3; 0 to 15% of Li.sub.2O; more than 0 but less than or equal to 12% of Na.sub.2O; 0 to 5% of K.sub.2O; more than 0 but less than or equal to 5% of ZrO.sub.2; 0 to 5% of P.sub.2O.sub.5; and 0 to 10% of TiO.sub.2. A crystalline phase contains at least one of R.sub.2SiO.sub.3, R.sub.2Si.sub.2O.sub.5, R.sub.2TiO.sub.3, R.sub.4Ti.sub.5O.sub.12, R.sub.3PO.sub.3, RAlSi.sub.2O.sub.6, RAlSiO.sub.4O.sub.10, R.sub.2Al.sub.2Si.sub.2O.sub.8, R.sub.4Al.sub.4Si.sub.5O.sub.18, quartz and quartz solid solution. With a liquidus temperature below 1,450° C., a thermal conductivity above 2 w/m.Math.k, and a Vickers hardness above 600 kgf/mm2, the glass ceramic is applicable to portable electronic devices and optical devices.