US Patent 7112549 Low thermal expansion ceramic and member for exposure system

A low-thermal-expansion, rigid and wear-resistant ceramic is provided. The low-thermal-expansion ceramic of the invention includes 60 vol % to 99.9 vol % of at least one selected from the group consisting of cordierite, spodumene and eucryptite and 0.1 vol % to 40 vol % of at least one selected from the group consisting of carbides, nitrides, borides and silicides of group IVa elements, group Va elements and group VIa elements, and boron carbide. The ceramic has a porosity of 0.5% or less and a thermal expansion coefficient, at 10° C. to 40° C., of 1.5×10−6/° C. or less.