Device for the support of a crystalline rod

A device for supporting a crystalline rod and a seed crystal during crucible-free zone melting, said device being coupled to the rotatable shaft of a zone-drawing apparatus, comprising:

• an externally threaded screw bolt mounted for rotation with the shaft, the top end of the screw bolt having an axially extending bore formed therein for receiving a seed crystal;
• at least two vertically pivotable swivel arms, the lower ends of which are pivotably mounted adjacent to the bore and the outer ends of which are movable radially outwardly and inwardly relative to the axis of said bore to define respectively an open and closed position of said arms;
• a ring coaxially surrounding the bolt and said inner ends of said arms and in sliding contact with said swivel arms and which is non-rotatably vertically movable so as to effect movement of said swivel arms between said open and closed positions;
• and
• means for non-rotatably vertically moving said ring so as to non-rotatably adjust the position of said swivel arms with respect to said bolt during the zone-melting operation.