Superconducting YBa2Cu3O7-x

Synthetic procedure from Colin Greaves, "Structural, Electrical and Magnetic Properties of Perovskite Ceramics," in Inorganic Experiments, edited by J. Derek Woolins, Wiley-VCH, 1994, pages 265-270 (ISBN 3527305106). See A. B. Ellis, " Superconductors: Better levitation through chemistry," J. Chem. Educ., 64(10), 836-841 (1987).

The magnetic flux of a magnet will not penetrate a superconducting material, enabling a magnet to be levitated on a superconducting material. In this experiment a pellet of YBa2Cu3Ox is prepared and cooled to its superconducting state in liquid nitrogen.

Safety Information

  • Wear eye protection
  • Thermal gloves recommended

Procedure:

  1. Dry reagents (Y2O3, CuO, and BaCO3) in an oven at 400°C for several hours.
  2. Weigh out a 1:2:3 molar ratio of Y:Ba:Cu (0.3023 g CuO, 0.5000 g BaCO3,and 0.1430 g Y2O3). Grind the materials to mix.
  3. Load 1/3 to 1/2 the material in a 13-mm diameter pellet die.
  4. Press at 5000 kg in a hydraulic press.
  5. Make two or three pellets total.
  6. Transfer the pellets to an alumina boat and load into an open quartz tube in a tube furnace.
  7. Heat at 930°C for 12 hours.
    Cool to 500°C and hold for 1 hour.
    Cool to 400°C over 30 minutes.
    Remove and/or cool to room temperature

Materials:

  • CuO, cupric oxide, Aldrich 450812, Acros AC40586
  • Y2O3, Aldrich 205168
  • BaCO3, Aldrich 237108, Fisher B30
  • 400°C muffle furnace, crucible
  • mortar and pestle
  • pellet die and press
  • 930°C tube furnace, alumina boat
  • small magnet, tweezers, foam cup, liquid nitrogen

Properties:

Cool a pellet in liquid nitrogen. An inverted foam cup makes an excellent insulating stand to hold the pellet. A magnet placed at the correct height above a superconducting pellet will levitate.
A levitating magnet supported by a superconductor can be freely spun.
Long term exposure to moisture may cause the pellet to crumble. A wax or polymer coating may help preserve the pellet.

YouTube Link:

http://www.youtube.com/watch?v=pJt8pFe9Vso