GB1416824A - Crystal growing - Google Patents

Abstract

1416824 Mixed single crystals PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 20 Feb 1973 [23 Feb 1972] 8272/73 Headings BIS and BIG A mixed single crystal is made from a liquid solution of the components of the crystal in a crucible rotatable about a horizontal axis by heating the solution to a temperature above the point of spontaneous nucleation, cooling the solution until nucleation occurs, rotating the crucible about its horizontal axis so that the warmest zone of the solution is contacted with replenishment quantities of the components and optionally a seed crystal is introduced into the coolest zone of the solution, localizing the crystallization by local cooling and when crystallization is completed, separating the liquid solution from the crystal by rotation of the crucible about its horizontal axis. The crucible may also be rotated about a vertical axis. The mixed single crystal formed is preferably one in which part of the iron in a yittrium-irongarnet is replaced by gallium. The method is preferably carried out as shown in the Figures. Figure 1 shows generally the crucible 9 positioned in the furnace with air inlets 2 and exhaust device 3, and insulation layers 4, 5 and 6. The crucible is held in position by holder 10, and is rotatable and swingable about shafts 13 and 14. On the outside of the crucible a desaeration tube 15 is provided whereby no liquid can leave the crucible when it is rotated. In Figs. 2-4, the crucible 9 which contains solution 19 and seed crystal 16 is shown in the starting position. The additional materials 17, are present in a second crucible 18 which contains apertures 19. Upon rotation of the crucible, Figure 3, the additional material via the apertures 19 contacts the solution 12, and the local cooling is effected by cooling finger 20 extending through the furnace. Figure 4, shows the position of the crucible after termination of the crystallization,