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.

A glass ceramic sintered body having a small dielectric loss in a high frequency band of 10 GHz or higher and a wiring substrate using the same are provided. The glass ceramic sintered body contains crystallized glass, an alumina filler, and silica. The content of the crystallized glass is 45 mass % to 85 mass %, the content of the alumina filler is 14.8 mass % to 50.1 mass % in terms of Al.sub.2O.sub.3, and the content of silica is 0.2 mass % to 4.9 mass % in terms of SiO.sub.2.

A glass-ceramic cooktop is provided that is made of glass-ceramic material with a flat upper side and an underside. The glass-ceramic material has transmittance values of greater than 0.1% in the visible light range in the total wavelength region greater than 420 nm, a light transmittance in the visible range of 0.8-2.5%, and a transmittance of 0-85% in the infrared at 1600 nm, and wherein the glass-ceramic material has high quartz mixed crystals as the prevalent crystal phase. The underside is flat, unstructured, and coplanar with the upper side.

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 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.