| 摘要 |
PURPOSE:When a single crystal of tellurium dioxide is made to grow by the drawing-up method, after its start, the melt of the raw material is gradually cooled to allow the seed crystal to become thicker gradually to form a bell shape with the flat bottom, thus producing a good-quality single crystal free from striae formation. CONSTITUTION:Tellurium dioxide is melted in a platinum crucible and the single crystal is made to grow by the drawing-up method. At this time, from its start or when the seed crystal comes to have a certain diameter, the melt of the raw material is gradually cooled to allow its diameter to become larger gradually, thus forming a shape of narrow bell or narrow cone 2 with flat or convexed bottom 3. Since the latent heat of solidification is also dissipated toward the melted raw material which is getting lower in its temperature, satisfactory heat dissipation is effected to cause uniform crystallization at the center and inhibit the striae formation. |
