| 摘要 |
PURPOSE:To synthesize a star corundum having excellent transparency and highly clear star, from Al2O3, TiO2 and a color-developing agent, by making a solid solution of Al2O3 and TiO2, adding the color-developing agent thereto, and using the mixture as the raw material. CONSTITUTION:A solid solution of Al2O3-TiO2 having TiO2-content of 0.1- 0.5wt% is prepared beforehand, pulverized, and mixed with a color-developing agent composed of powdery Cr2O3 or powdery TiO2 and Fe2O3. The mixture is filled in a tube in the form of a rod, and sintered at 1,200-1,600 deg.C. The sintered rod is used as a raw material, and converted to a ruby (when the color-developing agent is Cr2O3) or a sapphire (when the color-developing agent is TiO2 and Fe2O3) by conventional converging FZ process using a seed corundum crystal, and annealed at 1,100-1,600 deg.C for 12-30hr. A star corundum having excellent transparency and clear star pattern can be prepared by this process. |
