Method of producing aluminum oxynitride having improved optical characteristics

A method of preparing homogeneous aluminum oxynitride comprising the steps of:

• preparing a mixture of aluminum oxide and carbon black, the carbon content of said mixture being in the range of 5.4-7.1 weight percent;
• reacting in a flowing nitrogen atmosphere said mixture first at a temperature of approximately 1550.degree. C. for one hour, and then at a temperature of at least 1750.degree. C. for 40 minutes;
• and
• ball milling the reacted mixture to provide a powder having a particle size in the range of about 0.5 microns to 5 microns.

A method of producing transparent sintered aluminum oxynitride bodies comprising the steps of:

• preparing a mixture of aluminum oxide and carbon black, the carbon black content of said mixture being in the range of 5.4 to 7.1 weight percent;
• reacting said mixture in the presence of nitrogen and at a temperature in the range of 1550.degree.-1850.degree. C.;
• forming a pressed green body of predetermined shape from said mixture;
• placing said green body in a sintering chamber;
• providing at least one dopant in said chamber, said dopant selected from the group consisting of yttrium, lanthanum, and compounds thereof;
• and
• sintering said green body in a nitrogen atmosphere at a temperature higher than 1900.degree. C. but lower than the solidus temperature of aluminum oxynitride.