The present invention relates to a glass ceramic having a base composition including, in mol % in terms of oxides, 60% to 75% of SiO.sub.2, 3% to 20% of Al.sub.2O.sub.3, and 5% to 25% of Li.sub.2O, in which an average linear expansion coefficient at 250 C. to 350 C. is 9010.sup.7 [/K] or less, and when the glass ceramic is immersed in hot water at 80 C. for 120 minutes, a mass change amount per surface area from a mass of the glass ceramic before immersion is 1500 g/cm.sup.2 or less.

A glass-ceramic material includes an oxynitride glass with a chemical formula Ca.sub.7Al.sub.14Si.sub.17OsN.sub.7 and zinc oxide. The zinc oxide is present in an amount of 8 to 16 percent by weight based on the total weight of the glass-ceramic material. The zinc oxide is doped in the oxynitride glass. The glass-ceramic material has one or more conductive channels having a length of 100 to 1000 m and a width of 0.5 to 10 m.

It is demanded that a LTCC substrate composition capable of maintaining low relative permittivity k and high Q value without having a reactivity with a silver which is an electrode material and causing migration of the silver during a co-firing operation at a low temperature. Provided with a low temperature co-fired substrate composition containing 83 to 91 wt. % of CaOB.sub.2O.sub.3SiO.sub.2 based glass powder, 7.5 to 14 wt. % of two or more kinds of nanometer-sized SiO.sub.2 powders having different ranges of particle diameter and 1.5 to 3 wt. % of -wollastonite powder as a crystallization agent wherein the glass powder contains 40.0 to 45.0 wt. % of CaO, 9.0 to 20.0 wt. % of B.sub.2O.sub.3 and 40.0 to 46.0 wt. % of SiO.sub.2.

A glass article comprises an amorphous glass layer having an amorphous phase, and crystal particles dispersed in the amorphous glass layer and having a crystalline phase, wherein some of the crystal particles protrude from a surface of the amorphous glass layer.

A glass-ceramic article having one or more crystalline phases; a residual glass phase; a compressive stress layer extending from a first surface to a depth of compression (DOC); a maximum central tension greater than 70 MPa; a stored tensile energy greater than 22 J/m.sup.2; a fracture toughness greater than 1.0 MPam; and a haze less than 0.2.

The glass for covering a semiconductor element contains: in mol %, as a glass composition, SiO.sub.2: 20% to 36%, ZnO: 8% to 40%, B.sub.2O.sub.3: 10% to 24%, Al.sub.2O.sub.3: 10% to 20%, and MgO+CaO: 8% to 22%, in which SiO.sub.2/ZnO is 0.6 or more and less than 3.3 in terms of a molar ratio, and a lead component is substantially not contained.

A glass ceramic for an optical filter and an optical filter are obtained that have both thermal expansion characteristics for preventing refractive index fluctuations at a usage temperature of a filter member and mechanical characteristics considering durability, and further have excellent workability. An internal transmittance of the glass ceramic for an optical filter is 0.970 or more with respect to light having a wavelength of 1550 nm when a thickness of the glass ceramic is 1 mm. The glass ceramic includes, by mass % in terms of oxide, 40.0% to 70.0% of a SiO.sub.2 component, 11.0% to 25.0% of an Al.sub.2O.sub.3 component, 5.0% to 19.0% of a Na.sub.2O component, 0% to 9.0% of a K.sub.2O component, 1.0% to 18.0% of one or more components selected from a MgO component and a ZnO component, 0% to 3.0% of a CaO component, and 0.5% to 12.0% of a TiO.sub.2 component.

A silicate-based composition includes: 40-80 mol % SiO.sub.2, >0-25 mol % MO, 15-40 mol % R.sub.2O, >0-10 mol % Al.sub.2O.sub.3, >0-10 mol % P.sub.2O.sub.5, and >0-5 mol % ZrO.sub.2, such that MO is a sum of BeO, MgO, CaO, SrO, and BaO; and R.sub.2O is a sum of Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O, Cs.sub.2O.

The present invention relates to a glass ceramic including: at least one of a lithium disilicate type crystal and a solid solution crystal thereof; at least one of a virgilite type crystal and a solid solution crystal thereof; and a residual glass phase, in which a fracture toughness value K.sub.IC is 1.0 MPa.Math.m.sup.0.5 or more, and a haze value in terms of a thickness of 0.7 mm is 0.8% or less.

A glass-ceramic article having one or more crystalline phases; a residual glass phase; a compressive stress layer extending from a first surface to a depth of compression (DOC); a maximum central tension greater than 70 MPa; a stored tensile energy greater than 22 J/m.sup.2; a fracture toughness greater than 1.0 MPam; and a haze less than 0.2.