Cette page appartient aux archives web de l'EPFL et n'est plus tenue à jour.
This page belongs to EPFL's web archive and is no longer updated.

Presentation for the workshop

Now you can browse a presentation of PURE for the workshop in Noordwijk.

Description of the "Pure" experiment

The major challenge in contemporary industry is the availability of pure and clean crystals with perfect structure. That means without any unwanted impurities, and also with a perfect crystalline order. That offers much better potential in the technological applications (semiconductors, transistors, computer chips, ...) and enhance device performance.

The method usually used to get the best result is to heat the substrata to fusion temperature and then allow it to recrystallise in microgravity. Hence, the material, without undergoing convection and other gravity effects has more ideal crystalline structure.

Our goal is also to purify the crystal, but in a bit modified way by using zone refining. We will also locally heat the material with a coil, but only to about 2/3 of the fusion temperature and move the temperature peak through the whole sample. The effect will be, as in usual zone refining, that the dislocations and the impurities will move because of the temperature gradient.

Our goal is to understand the role of gravity in the movement of the impurities and dislocations due to temperature gradient. We expect that in microgravity the purification quality will be enhanced. In summary, we want to perform this experiment because:

  • it will work as it is just a modification of an experiment that already works
  • it hasn t been done before
  • it is important to understand this phenomena for fundamental sciences and industry point of view
Posted by Alexei Altoukhov on Saturday 8 April 2006 at 0:19