| 摘要 |
961,281. Crystal pulling. PHILIPS ELECTRICAL INDUSTRIES Ltd. April 16, 1963 [April 18, 1962], No. 14842/63. Heading B1S. A rod of a peritectic compound or mixed crystal is pulled from a melt of a different composition, said melt being of small volume and being replenished by melt which is of the same composition as the rod and which is fed from a large volume of melt in a reservoir maintained at a temperature higher than that of the melt being replenished. A peritectic rod of Tl 2 Te 3 may be pulled at 3 mm./hr. from a melt containing 29-34 atom per cent of Tl at 250 ‹C., the replenishing melt being at 320 ‹C. The rod may initially be of T1Te and the crystallizing melt may initially be of Tl 2 Te 3 at 300 ‹C., the temperature being lowered as pulling proceeds. A mixed crystal rod of equal quantities of Bi 2 Te 3 and Sb 2 Te 3 may be pulled at 4 mm./hr. from a melt containing 37% of SbTe at 600 ‹C., the replenishing melt being at 610 ‹C. The rod may initially be of SbTe and the crystallizing melt may initially be the same as the replenishing melt. As shown, a rod 21 is pulled in a vessel 1 from a melt 20 the temperature of which is controlled by a resistance heating furnace 7. Melt 20 is replenished under the action of gravity by melt 22 in a reservoir 9 connected to vessel 1 by a capillary tube 8. The temperatures of melt in reservoir 9 and capillary tube 8 are controlled by resistance heating furnaces 11 and 10. Hydrogen is passed through the apparatus via inlet 14, tube 16, cock 18, and outlet 15 during pulling. An increased pressure in reservoir 9 may be provided at the commencement of pulling by turning cock 18. Rod 21 may be rotated during pulling. In another embodiment, Fig. 2 (not shown), a controlled difference in pressure between the atmospheres above the crystallizing melt and the melt in the reservoir is used to supply the replenishing melt. A rod of a compound having a volatile constituent may be pulled from a melt containing a lower proportion of the volatile constituent, the vapour pressure of the volatile constituent being less above the crystallizing melt than above the melt in the reservoir. |
