| 摘要 |
PURPOSE:In the production of blue sapphire by the floating zone method using crystals of corundum as seeds, SiO2 is added to the starting mixture and the crystals synthesized is annealed to enable the high-efficiency production of large- size crystals showing clear starts. CONSTITUTION:Alumina, as a major constituent, is combined with Fe2O3 and TiO2 as colorant, and SiO2 as a stabilizer and the mixture is made uniform by the wet method. The resultant mixture is charged in a rubber tube and formed into a cylindrical bar by the rubber press method. The resultant bar is sintered in an electric furnace at 1,500-1,700 deg.C. The bar is used as a starting material, corundum crystals are used as seeds to produce blue sapphire by the floating zone method. This process enables high-efficiency production of uniformly colored crystals. Then, the crystal is annealed at 1,000-1,500 deg.C in an oxidative atmosphere to precipitate needle crystals of titanium oxide and cut and ground to give a star blue sapphire. |
