A glass ceramic substrate contains a glass ceramic having a compressive stress layer on a surface thereof and a crystalline phase containing LiAlSi.sub.4O.sub.10, quartz, and quartz solid solution. The glass ceramic has 60 to 80% of SiO.sub.2, 4 to 20% of Al.sub.2O.sub.3, more than 0 but less than or equal 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. The quartz and the quartz solid solution crystalline phase account for 15 to 30% of the glass ceramic by wt %, the LiAlSi.sub.4O.sub.10 crystalline phase accounts for not greater than 15% of the glass ceramic by wt %, and a ratio of ZrO.sub.2/Li.sub.2O is more than 0 but less than or equal to 0.35.

A microcrystalline glass product. The microcrystalline glass product includes the following components in percentage by weight: SiO.sub.2: 45-70%; Al.sub.2O.sub.3: 8-18%; Li.sub.2O: 10-25%; ZrO.sub.2: 5-15%; P.sub.2O.sub.5: 2-10%; and Y.sub.2O.sub.3: greater than 0 but less than or equal to 8%. Through reasonable component design, the microcrystalline glass and the microcrystalline glass product have excellent mechanical and optical properties and are suitable for electronic devices or display devices.

Provided is reinforced crystallized glass that has a high strength and is less likely to break. The reinforced crystallized glass includes a compressive stress layer on a surface, and [CS.sub.50 μm*(DOL.sub.zero−50)]/2 is 2000 or more, where CS.sub.50 μm (MPa) is a compressive stress at a depth of 50 μm from an outermost surface, and DOL.sub.zero (μm) is a stress depth when the compressive stress is 0 MPa.

Provided are crystallized glass that is easy to process and in which a high compressive stress value can be obtained on a surface, and reinforced crystallized glass thereof. A crystallized glass containing at least one type selected from α-cristobalite and an α-cristobalite solid solution as a main crystal phase, in which, by mass % in terms of oxide, a content of a SiO.sub.2 component is 50.0% to 75.0%, a content of a Li.sub.2O component is 3.0% to 10.0%, a content of an Al.sub.2O.sub.3 component is 5.0% or more and less than 15.0%, and a content of a B.sub.2O.sub.3 component is more than 0% and 10.0% or less.

A crystallized glass contains: from 58 to 70% of SiO.sub.2, from 15 to 30% of Al.sub.2O.sub.3, from 2 to 10% of Li.sub.2O, from 0 to 10% of Na.sub.2O, from 0 to 10% of K.sub.2O, from 0 to 15% of Na.sub.2O+K.sub.2O, from 0 to 15% of MgO+CaO+SiO+BaO+ZnO, from 0.1 to 6% of SnO.sub.2, from 0.5 to 6% of ZrO.sub.2, from 0 to 4% of TiO.sub.2, and from 0 to 6% of P.sub.2O.sub.5 in mass %, in which the crystallized glass has a degree of crystallinity of 1 to 95%, and an average visible light transmittance of 50% or greater at a thickness of 0.8 mm and a wavelength of 380 to 780 nm, and a compression stress layer is formed on a surface.

A glass-ceramic includes glass and crystalline phases, where the crystalline phase includes non-stoichiometric suboxides of titanium, forming ‘bronze’-type solid state defect structures in which vacancies are occupied with dopant cations.

A microcrystalline glass and microcrystalline glass product with excellent mechanical properties, microcrystalline glass product, the components of which, expressed in weight percent, contain: SiO.sub.2: 65˜80%; Al.sub.2O.sub.3: below 5%; Li.sub.2O: 10˜25%; ZrO.sub.2: 5˜15%; P.sub.2O.sub.5: 1˜8%. Through the reasonable component design, the microcrystalline glass product has excellent mechanical properties.

Lithium silicate materials are described which can be easily processed by machining to dental products without undue wear of the tools.

A low infrared absorbing lithium glass includes FeO in the range of 0.0005-0.015 wt %, more preferably 0.001-0.010 wt %, and a redox ratio in the range of 0.005-0.15, more preferably in the range of 0.005-010. The glass can be chemically tempered and used to provide a ballistic viewing cover for night vision goggles or scope. A method is provided to change a glass making process from making a high infrared absorbing lithium glass having FeO in the range of 0.02 to 0.04 wt % and a redox ratio in the range of 0.2 to 0.4 to the low infrared absorbing lithium glass by adding additional oxidizers to the batch materials. A second method is provided to change a glass making process from making a low infrared absorbing lithium glass to the high infrared absorbing lithium glass by adding additional reducers to the batch material. In one embodiment of the invention the oxidizer is CeO.sub.2. An embodiment of the invention covers a glass made according to the method.

Embodiments of a glass-ceramic, glass-ceramic article or glass-ceramic window that includes 40 mol %≤SiO.sub.2≤80 mol %; 1 mol %≤AI.sub.2O.sub.3≤15 mol %; 3 mol %≤B.sub.2O.sub.3≤50 mol %; 0 mol %≤R.sub.2O≤15 mol %; 0 mol %≤RO≤2 mol %; 0 mol %≤P.sub.2O.sub.5≤3 mol %; 0 mol %≤SnO.sub.2≤0.5 mol %; 0.1 mol %≤MoO.sub.3≤15 mol %; and 0 mol %≤WO.sub.3≤10 mol % (or 0 mol %<MoO.sub.3≤15 mol %; 0.1 mol %≤WO.sub.3≤10 mol %; and 0.01 mol %≤V.sub.2O.sub.5≤0.2 mol %), wherein the WO.sub.3 (mol %) plus the MoO.sub.3 (mol %) is from 1 mol % to 19 mol %, and wherein R.sub.2O (mol %) minus the AI.sub.2O.sub.3 (mol %) is from −12 mol % to 4 mol %, are disclosed.