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How do I Make Synthetic Garnet?

Synthetic garnets are made using a process called the Czochralski pulling technique. Jan Czochralski, a Polish chemist, accidentally dipped his pen into a crucible of molten tin instead of into his inkwell. He pulled out the pen and noticed a thin string of solidified metal attached to the nib. He confirmed that the string of crystallized metal was actually a single crystal. Repeating and expanding the process, he soon produced crystals one millimeter in diameter and as long as 150 centimeters.

Things You'll Need

Gadolinium powder
Gallium powder
Crucible and lid of platinum, iridium, graphite or ceramic
Pulling rod
Seed crystal
Zirconia insulated chamber
Heat Coil
Vented glass dome

Instructions

Czochralski Pull Method
- 1
  Monocrystalline gadolinium gallium garnet (GGG) is prepared using the Czochralski pull method from a melt composed of oxides of gadolinium and gallium. Place the ingredient powders in a crucible made of platinum, iridium, graphite or ceramic, and melt using heat coils in an insulated chamber.
- 2
  Attach a seed crystal to one end of a rotating rod in the lid of the chamber, and lower the rod into the crucible until it just contacts the melt.
- 3
  Slowly withdraw the rod as the seed crystal collects material from the melt, and the material cools and solidifies. As long as the crystal remains in contact with the melt, the crystal will continue to grow until the material in the melt is completely depleted. Crystals formed using this method can be very large, up to 500 millimeters in diameter and one meter in length. They also have a high degree of purity, making them desirable for use as gemstones.

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