Provided is a glass material that can satisfy both a high Faraday effect and a high light transmittance in a short wavelength range. A glass material contains, in % by mole, 30 to 50% Pr.sub.2O.sub.3 and 0.1 to 70% B.sub.2O.sub.3+P.sub.2O.sub.5.

Provided is a glass material that can satisfy both a high Faraday effect and a high light transmittance in a short wavelength range. A glass material contains, in % by mole, 30 to 50% Pr.sub.2O.sub.3 and 0.1 to 70% B.sub.2O.sub.3+P.sub.2O.sub.5.

Provided are an optical glass that has optical properties including a medium refractive index and low dispersion and that has good chemical durability and a low specific gravity, and a preform material and an optical element that use the optical glass.

The optical glass contains a SiO.sub.2 component: 0% or more and less than 30.0%; 8.0% to 30.0% of an Al.sub.2O.sub.3 component; less than 20.0% of an RO component (where R represents at least one selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) in terms of a mass sum; and 10.0% to 55.0% of an Ln.sub.2O.sub.3 component (where Ln represents at least one selected from the group consisting of La, Gd, Y, and Lu) in terms of a mass sum.

A mass ratio (SiO.sub.2+Al.sub.2O.sub.3)/B.sub.2O.sub.3 is 0.3 to 10.0, and the optical glass has a refractive index (n.sub.d) of 1.58 or more and 1.80 or less and an Abbe number (.sub.d) of 35 or more and 65 or less.

Provided are an optical glass that has optical properties including a medium refractive index and low dispersion and that has good chemical durability and a low specific gravity, and a preform material and an optical element that use the optical glass.

The optical glass contains a SiO.sub.2 component: 0% or more and less than 30.0%; 8.0% to 30.0% of an Al.sub.2O.sub.3 component; less than 20.0% of an RO component (where R represents at least one selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) in terms of a mass sum; and 10.0% to 55.0% of an Ln.sub.2O.sub.3 component (where Ln represents at least one selected from the group consisting of La, Gd, Y, and Lu) in terms of a mass sum.

A mass ratio (SiO.sub.2+Al.sub.2O.sub.3)/B.sub.2O.sub.3 is 0.3 to 10.0, and the optical glass has a refractive index (n.sub.d) of 1.58 or more and 1.80 or less and an Abbe number (.sub.d) of 35 or more and 65 or less.

Provided is optical glass containing, in terms of mol % of cations: 10 to 60% of a La.sup.3+ component; more than 0% and up to 75% of a Ga.sup.3+ component; and 5 to 75% of a Nb.sup.5+ component, in which a total amount of the La.sup.3+ component, Ga.sup.3+ component, and Nb.sup.5+ component is 60 to 100%.

The invention a ward for improving health belongs to the ward field. The ward includes glass window, characterized in that all or part of the glass window has glass structure which can be penetrated through by UVB, and the glass structure is a controllable glass structure, the controllable glass structure is a glass structure, of which UVB transmission amount is controllable. It's verified that, the ward of the invention can make patients get sufficient UVB exposure so as to meet the needs of synthesis of vitamin D in organism in the limited time, compared to ordinary ward and regular outdoor sunlight, the effect of vitamin D synthesis is better, and patients don't need to walk, which is very convenient for bedridden or disabled patients.

A varistor composition free of Sb comprising: (a) ZnO; (b) BBiZnPr glass, or BBiZnLa glass, or a mixture thereof; (c) a cobalt compound, a chromium compound, a nickel compound, a manganese compound, or mixtures thereof; (d) SnO.sub.2; and (e) an aluminum compound, a silver compound, or a mixture thereof. By adjusting the ratio between the components, the varistor composition may be made into a multilayer varistor with inner electrodes having a low concentration of noble metals at a sintering temperature less than 1200 C. The multilayer varistor made from the varistor composition has good maximum surge current, good ESD withstand ability, and low fabrication cost.

A varistor composition free of Sb comprising: (a) ZnO; (b) BBiZnPr glass, or BBiZnLa glass, or a mixture thereof; (c) a cobalt compound, a chromium compound, a nickel compound, a manganese compound, or mixtures thereof; (d) SnO.sub.2; and (e) an aluminum compound, a silver compound, or a mixture thereof. By adjusting the ratio between the components, the varistor composition may be made into a multilayer varistor with inner electrodes having a low concentration of noble metals at a sintering temperature less than 1200 C. The multilayer varistor made from the varistor composition has good maximum surge current, good ESD withstand ability, and low fabrication cost.

An optical glass has a refractive index (n.sub.d) of 1.55 or more. A difference (Tf?Tg) between a fictive temperature (Tf) and a glass transition temperature (Tg) of the optical glass is 0? C. or more. The optical glass may have a crack initiation load L of 350 mN or more.

Provided is a glass composition that exhibits greater Faraday effect than ever before. A glass composition contains 48% or more of Tb.sub.2O.sub.3 (exclusive of 48%) in % by mole.