| 摘要 |
PURPOSE:To keep the composition of a single crystal uniform and to restrict the amount of platinum entering the crystal when the crystal is manufactured by the Bridgeman method, by melting a starting material from the lower end and growing a single crystal while forming a melt zone. CONSTITUTION:Upper and lower platinum crucibles 1, 2 are placed in two steps, a rodlike starting material 3 is suspended in the crucible 1, and a spout 4 is attached to the bottom of the crucible 1. Both the crucibles are slowly lowered in a furnace having a temp. gradient shown by each right curve. When the lower end of the material 3 reaches a point A at which the furnace is kept at the melting start temp., the material 3 is melted and flows into the crucible 2 to form a melt zone 5. When the lower end of the crucible 2 reaches a point B at which the furnace is kept at the recrystallization temp., the lower end of the zone 5 is cooled to the crystallization temp. or below and the formation of a single crystal 6 is started by crystallization from the lower end of the zone 5. The feed of the molten material 3 into the crucible 2 and the crystallization are continued to control the zone 5 to a fixed width (d), and the single crystal 6 is grown. |
