How to Make a Superconductor

Superconductors can conduct electricity without resistance. They presently do so at very cold temperatures, often below the temperature of liquid nitrogen, which boils at -321 Fahrenheit. Superconductors that are not one element are usually made by combining different elements. There are hundreds of such superconductors, each with a different method of preparation. In most cases, intimate mixing of the elements, pressure and baking at high temperatures are required steps in the process of making superconductors. The description here is specifically for the superconductor called magnesium diboride, MgB2, discovered in 2001 and whose transition temperature is 39 degrees Kelvin. Since 2001 more sophisticated methods than described here have been developed for preparing magnesium diboride as films, tapes and wires.

Things You'll Need

  • Magnesium powder(99.999% purity)
  • Boron powder (99.999% purity)
  • Glove box
  • Argon gas
  • Manual pellet press machine
  • Tube sealing machine
  • Analytical weighing balance
  • Pestle and mortar
  • Test tubes
  • Test-tube sealer
  • Isostatic press
  • Liquid helium
  • Strong disk magnet
  • Tantalum foil
  • Hot isostatic press (HIP) furnace
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Instructions

  1. Weighing, Mixing and Baking Magnesium Diboride

    • 1

      Purchase magnesium and boron samples with 99.99 percent purity. Weigh, using the analytical balance, one mole of magnesium powder to 2 moles of Boron power. One mole of Mg weighs 24.31 grams and two moles of Boron weighs 21.62 grams.

    • 2

      Mix the weighed portions of magnesium and boron in a glovebox mortar and grind them to an intimate sample in an atmosphere of argon.

    • 3

      Convert the mixed powder into pellets using a manual pelleting press machine. Obtain many pellet samples about 2mm thick.

    • 4

      Wrap pellets with Tantalum foil. Place in a quartz tube flushed of air with argon gas at very high pressure of up to 196 megapascal (mpa). Seal the tube with a sealing machine.Place in a hot isostatic press (HIP) furnace. Heat to 973 degrees Celsius for at least 10 hours.

    • 5

      Turn off the furnace, and slowly cool sample to room temperature. Cut open the tube and bring out a sample pellet for testing for superconductivity.

    • 6

      Plunge the sample in liquid helium to cool for 30 minutes. Test for superconductivity by placing a small thin disk magnet over a dewar containing the sample. The magnet will be repelled if the sample is superconducting. Otherwise, regrind the other samples, pellet them and repeat the heating process for another 20 hours.

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