BLUE-COLORED ALUMINUM OXIDE SINGLE CRYSTAL AND METHOD FOR PRODUCING ALUMINUM OXIDE SINGLE CRYSTAL

• Main Authors: ASAKA, Shohei, KAWAMINAMI, Shuichi, TAKAHASHI, Maki
• Format: Patent
• Language: English; French; German
• Published: 06.03.2019
• Subjects: AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUSPOLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR; CHEMISTRY; CRYSTAL GROWTH; METALLURGY; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE; REFINING BY ZONE-MELTING OF MATERIAL; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE; SINGLE-CRYSTAL-GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL ORUNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL

An object of the present invention is to provide, at an industrially reasonable cost, an aluminum oxide single crystal having a bright blue color, such as a color called sky blue or marine blue, even inside the crystal. In the present invention, a crystal is grown from a raw material having a cobalt concentration of 1700 to 13700 ppm relative to aluminum atoms by a flame fusion method using oxyhydrogen flame. Alternatively, a crystal is grown from a raw material having a cobalt concentration of 5000 ppm to 20000 ppm relative to aluminum atoms by a Rotating and pulling method. Subsequently, the crystal is heat-treated at a predetermined temperature in an atmosphere having an oxygen partial pressure of 10 -6 atm to 10 -9 atm. An aluminum oxide single crystal having a blue color and having a cobalt concentration of 50 ppm to 130 ppm relative to the number of aluminum atoms can be produced by this production method.