An alkali-free glass of the present invention includes as a glass composition, in terms of mass %, 55% to 70% of SiO.sub.2, 15% to 25% of Al.sub.2O.sub.3, 0% to 1% of B.sub.2O.sub.3, 0% to 0.5% of Li.sub.2O+Na.sub.2O+K.sub.2O, 2% to 6% of MgO, 2% to 8% of CaO, 0% to 4% of SrO, and 6% to 12% of BaO, and has a strain point of more than 720° C.

An optical fiber includes a glass portion, a primary coating layer, and a secondary coating layer. In the optical fiber, a value of microbend loss characteristic factor F.sub.μBL_GO is 2.6 ([GPa.sup.−1.Math.μm.sup.−10.5.Math.dB/turn].Math.10.sup.−27) or less, when represented by

F.sub.μBL_GO=F.sub.μBL_G×F.sub.μBL_O

by using geometry microbend loss characteristic F.sub.μBL_G and optical microbend loss characteristic F.sub.μBL_O.

A method of forming an optical fiber, including: exposing a soot core preform to a dopant gas at a pressure of from 1.5 atm to 40 atm, the soot core preform comprising silica, the dopant gas comprising a first halogen doping precursor and a second halogen doping precursor, the first halogen doping precursor doping the soot core preform with a first halogen dopant and the second halogen precursor doping the soot core preform with a second halogen dopant; and sintering the soot core preform to form a halogen-doped closed-pore body, the halogen-doped closed-pore body having a combined concentration of the first halogen dopant and the second halogen dopant of at least 2.0 wt %.

An alkali-free glass of the present invention includes as a glass composition, in terms of mass %, 55% to 70% of SiO.sub.2, 15% to 25% of Al.sub.2O.sub.3, 0% to 1% of B.sub.2O.sub.3, 0% to 0.5% of Li.sub.2O+Na.sub.2O+K.sub.2O, 2% to 6% of MgO, 2% to 8% of CaO, 0% to 4% of SrO, and 6% to 12% of BaO, and has a strain point of more than 720° C.

A multilayer coil component includes a component element assembly in which an inner conductor is disposed and an outer electrode disposed on the surface of the component element assembly. The component element assembly includes a first dielectric glass layer in which the inner conductor is embedded and second dielectric glass layers that are thin layers disposed on respective principal surfaces of the first dielectric glass layer. The primary component of each of the first dielectric glass layer and the second dielectric glass layers is formed of a glass material and has a filler component containing at least quartz, and the second dielectric glass layers have a lower quartz content than the first dielectric glass layer.

An alkali free glass has an average coefficient of thermal expansion at 50 to 350° C. of 30×10.sup.−7 to 43×10.sup.−7/° C., a Young's modulus of 88 GPa or more, a strain point of 650 to 725° C., a temperature T.sub.4 at which a viscosity reaches 10.sup.4 dPa.Math.s of 1,290° C. or lower, a glass surface devitrification temperature (T.sub.c) of T.sub.4+20° C. or lower, and a temperature T.sub.2 at which the viscosity reaches 10.sup.2 dPa.Math.s of 1,680° C. or lower. The alkali free glass contains, as represented by mol % based on oxides, 62 to 67% of SiO.sub.2, 12.5 to 16.5% of Al.sub.2O.sub.3, 0 to 3% of B.sub.2O.sub.3, 8 to 13% of MgO, 6 to 12% of CaO, 0.5 to 4% of SrO, and 0 to 0.5% of BaO. MgO+CaO+SrO+BaO is 18 to 22%, and MgO/CaO is 0.8 to 1.33.

A glass element has, per kg of glass, 50 or fewer inclusions having a size of 2 μm to 10 μm. The glass element can be made of borosilicate glass.

A glass article is designed at least in part in the form of a glass tube element including at least one shell which encloses at least one lumen. For at least one light transmission analysis of the glass article, a ratio of an average amplitude transmission factor and a specific amplitude transmission factor is greater than 1.00001.

Glass-based articles are manufactured by a unique ion exchange process that results in glass-based articles having improved stress profiles with higher stress values at moderate depths. A medium of the ion exchange process includes ions of two or more alkali metals of two or more alkali metal oxides in a base composition of a glass-based substrate in a ratio such that ions of each alkali metal are in chemical equilibrium with each of the respective alkali metals of the alkali metal oxides in the base glass composition.

An alkali free glass has an average coefficient of thermal expansion at 50 to 350° C. of 30×10.sup.−7 to 43×10.sup.−7/° C., a Young's modulus of 88 GPa or more, a strain point of 650 to 725° C., a temperature T.sub.4 at which a viscosity reaches 10.sup.4 dPa.Math.s of 1,290° C. or lower, a glass surface devitrification temperature (T.sub.c) of T.sub.4+20° C. or lower, and a temperature T.sub.2 at which the viscosity reaches 10.sup.2 dPa.Math.s of 1,680° C. or lower. The alkali free glass contains, as represented by mol % based on oxides, 62 to 67% of SiO.sub.2, 12.5 to 16.5% of Al.sub.2O.sub.3, 0 to 3% of B.sub.2O.sub.3, 8 to 13% of MgO, 6 to 12% of CaO, 0.5 to 4% of SrO, and 0 to 0.5% of BaO. MgO+CaO+SrO+BaO is 18 to 22%, and MgO/CaO is 0.8 to 1.33.