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.
- Wear eye protection
- Thermal gloves recommended
- Dry reagents (Y2O3, CuO, and BaCO3) in an oven at 400°C for several hours.
- 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.
- Load 1/3 to 1/2 the material in a 13-mm diameter pellet die.
- Press at 5000 kg in a hydraulic press.
- Make two or three pellets total.
- Transfer the pellets to an alumina boat and load into an open quartz tube in a tube furnace.
- 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
- 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
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.