| 摘要 |
PURPOSE:To stably obtain a homogeneous spinel sintered compact excellent in transparency and to improve its productivity by heat-treating the spinel powder obtained by thermally decomposing its sulfate to reduce the residual sulfur to a specific value or below and then crushing the powder to a specified grain diameter. CONSTITUTION:The spinel powder obtained by thermally decomposing its sulfate is heat-treated at about 700-1400 deg.C to reduce the residual sulfur to <=100ppm and then crushed to control the average grain diameter to <1mum, and a desired spinel powder is obtained. The powder is reheated for 1-10hr. The reheating is conducted in the atmosphere, oxygen-contg. atmosphere, reducing atmosphere of hydrogen, etc., and atmosphere of an inert gas such as argon and helium or in vacuum. The atmospheres are appropriately selected in accordance with the shape of the residual sulfur, reheating temp., etc. |
