| 摘要 |
PURPOSE: To obtain a good-quality single crystal which is designed for a VHS format and has decreased crystal defects and platinum inclusions by gradually passing a molten raw material into a furnace having a temp. gradient and allowing a single crystal to grow by using a specific seed crystal. CONSTITUTION: A bar-shaped ferrite raw material 3 is inserted into an upper crucible 1 made of platinum hung down from above. A seed crystal 7 whose longitudinal direction is a <-111> crystal direction is packed into the front end of a lower crucible 2 made of platinum supported from below by a supporting tube. These crucibles 1, 2 are gradually lowered into the furnace having the temp. gradient shown by a model on the right side. The raw material 3 melts and flows down from the pouring port 4 of the crucible 1 into the crucible 2 and forms a melt zone 5 of a molten state when the bottom end of the raw material 3 arrives at the point X in the furnace which is the melt initiation temp. of the raw material 3. The Mn-Zn based ferrite single crystal in the <-111> crystal direction crystallizes successively from the bottom end of the melt zone 5 when the bottom end of the crucible 2 arrives at the Y point of the crystallization temp. in the furnace. This crystal grows to a single crystal ingot 6. |
