| 摘要 |
[Problems] To provide a method of producing, easily and in a high yield, a reformed aluminum nitride sintered body having very excellent light transmission property which can be favorably used as a light-transmitting cover particularly for light sources having high luminous efficiencies. [Means for Solution] An aluminum nitride sintered body having a concentration of metal impurities excluding aluminum of not more than 150 ppm, an oxygen concentration of not more than 0.5% by weight and a relative density of not less than 95% is used as a starting material. The aluminum nitride sintered body is heat-treated in an oxidizing atmosphere in a temperature region of 1400 to 2000° C. to increase the oxygen concentration by not less than 0.03% by weight. |
