Transparent rare-earth oxide sintered body and manufacturing method thereof

A manufacturing method of a transparent yttrium oxide sintered body, comprising:

• adding at least one of niobium and a niobium compound to a yttrium oxide powder to blend therewith;
• forming the blended material to a yttrium oxide molded body containing the niobium;
• and
• sintering the yttrium oxide molded body at 1700° C. or more and 2000° C. or less under a vacuum, hydrogen or rare gas atmosphere to form a transparent yttrium oxide sintered body comprising yttrium oxide as a main component and niobium in solid solution with the yttrium oxide, wherein in-line transmittance when a thickness of the yttrium oxide sintered body is 1 mm in a visible wavelength region in a range of 400 to 800 nm is 60% or more.

A transparent yttrium oxide sintered body, comprising:

• yttrium oxide as a main component;
• and
• niobium;
• wherein the niobium is contained in a range of 0.05 to 0.2 wt % in terms of metal,
• wherein the in-line transmittance at a thickness of 1 mm in a visible wavelength region in a range of 400 to 800 nm is 60% or more and no striae is contained.