Apparatus for producing monocrystals

Claim 1

Apparatus for producing monocrystals by crucible free zone melting, wherein the molten zone moves upwardly along a rod from which the monocrystal is produced and wherein the monocrystal includes a seed crystal, a neck portion continuing therefrom, a conical transitional zone and a substantially cylindrical main part, said apparatus inlcuding a chamber for the formation of a protective atmosphere, heating means for the production of melting heat for the molten zone, driving means for the mechanical movements necessary for the crystal formation, mounting means for the seed crystal, and supporting means which is applicable to the monocrystal beyond the conical portion and below the molten zone for supporting the monocrystal in the given orientation thereof comprising a plurality of rotationally symmetrical gripping means distributed about the circumference of the monocrystal and outer inwardly and downwardly sloping walls with which the gripping means are in contact, and means for raising and for lowering said gripping means having an upper surface for supporting the gripping means whereby on lowering, the gripping means are first caused by the sloping walls to perform a radial approach to the monocrystal until contact is made therewith to adapt the gripping means to the substantially cylindrical surface geometry and to the position of the monocrystal, and on further lowering thereafter increasing the gripping force all without moving the monocrystal out of its given orientation and maintaining the gripping means in a gripping position.