| 摘要 |
<p>The conical bottom end (a1) of the rod (a) is attached to a seed crystal (b). Zone (a1) is supported by a viscous mass (c) which solidified on cooling and forms an envelope round the cone (a1); and the mass (c) rests on a pedestal (d) made of thermally insulating material. Mass (c) pref. consists of a molten metal, e.g. Al, Pb, Sn, or Zn, or a molten alloy; or molten chlorides, esp. those of Ag or Cu; or a glass with low m.pt. The mass (c) is pref. heated in a storage vessel, from which it is driven by inert gas pressure to surround zone (a1). Mass (c) may alternatively consist of a rapid-setting cement mortar; or grains of metal or glass with low m.pt first melted when surrounding zone (a1), esp. via. a laser beam. Pedestal (d) is pref. ceramic, alumina, or Si3N4. Monocrystalline Si rods (a) more than 80 cm long and 60 mm dia. can be adequately supported and vibration of the bottom end of the rod prevented; such vibration often means that drawing must be stopped.</p> |
