Patent ID: 7749931

Claim:
A ceramic material for an optical member which shows black, wherein the ceramic material comprises a reaction-sintered sintered ceramic body prepared by synthesizing a formed body of a mixture comprising a ceramic raw material and a component that accelerates blackening, making use of a reaction sintering; wherein the ceramic material is a porous body having a porosity of 10% or more, the component that accelerates blackening is present in an amount of from 6 to 15 wt %, the maximum reflectance in the visible light region of from 380 to 800 nm on any point of the ceramic material is 2% or less, and the dimensions of the sintered ceramic body are within ±1% with respect to the dimensions of the formed body, and wherein the ceramic material comprises: at least one species of elements selected from Lu, Ce, Pr, Dy, Ho, Nb, W, Ta, Co, Cr, Mo, Hf, Ta, Zr, Ti, Fe, B and C as the blackening-accelerant component; and a crystal phase of at least one of silicon nitride, SIALON, silicon carbide, boron carbide and boron nitride, and a complex thereof.