GB1205544A - Method and apparatus for growing crystalline materials - Google Patents

Abstract

1,205,544. Crystal-pulling. TYCO LABORATORIES Inc. 9 Jan., 1969 [24 Jan., 1968], No. 1438/69. Heading BIS. A crystalline rod is pulled, using a seed, from ,a liquid in the form of a film on-the upper surface of a forming member having sharp boundary edge or edges which define the cross-section of the rod, the forming member having at least one passage for feeding liquid from a heated crucible to the upper surface by pressure or capillary action. A capillary passage may be a tube or slot (which may extend right across the upper surface). The forming member may be supported at the base of the crucible or may be suspended from a crucible cover. The seed may be smaller or larger than the capillary. The rod 'may be of alumina, barium titanate, yttrium aluminium garnet, lithium niobate, or sodium chloride. Growth of a-alumina may be along the c-axis (0001). A narrow filament having a diameter of 0.005-0.10 inch may be produced. In Fig. 2, a forming member 56 is situated in a crucible 46 having a cover 52, the member having a base 60 and an upper surface 64 which is of circular cross-section and extends through the cover and is connected via an axial capillary bore 62 and radial openings 63 to the liquid within the crucible. In Fig. 3, a seed 72 is pulled upwards from a film 70 on the surface 64. The base of the forming member may alternatively have a depending skirt (Fig. 5). The upper surface may alternatively be triangular (Fig. 5A), rectangular (Fig. 6 and 7), or annular (Fig. 8 and 8A). The crucible is contained in a suitable induction heating furnace (Fig. 1).