Tuesday, June 22, 2004
Super conductor demonstrating the Meissner magnetic levitation effect:
A samarium-cobalt magnet floats above a handmade disk of YBa2Cu3O7.X, a high temperature ceramic superconductor.
These are easy to make providing you have access to the chemicals, a muffle furnace and a press of some sort:
- Obtain some yttrium oxide, barium carbonate and copper oxide.
- The pellets weigh about two grams each. Mix them in the proportion of one mole of yttrium to two moles of barium to three moles of copper.
- Grind the solids togeter in a mortar and pestle until you have a fine powder.
- Put the powder into a crucible and cook it for four hours between 900°C and 1000°C.
- Take the mixture out of the furnace and grind it back into a fine powder.
- Put the powder into a press or pile it into the center of a brass washer about a millimeter thick.
- If you use a washer, set it on a piece of copper sheet, and put another piece of copper on top of it.
- Whack it hard and square with a hammer once.
- Slide the washer onto a ceramic planchette, that is, a small tile.
- Carefully remove the copper and the washer from the disk. If the disk falls apart, try again with a bit more powder.
- Put the panchette into a 'muffle' furnace and heat the disks quickly as close to 1000°C as you can get, but do not exceed this temperature.
- Cook the disk for 24 hours or so with the furnace's door open so that air can circulate freely.
- Slowly reduce the temperature of the furnace to room temperature over six hours or so.
- The disk is now ready to use. Put the disk on the bottom of a styrofoam cup and poured a amall bit of liquid nitrogen onto it. (I get LN2 from Praxair where it's about twenty bucks a gallon.)
- Carefully set a samarium cobalt (or other high gauss) magnet onto the cold disk. It should float like the one shown above.
CAUTION: Handle the chemical carefully, since they are toxic (especially barium carbonate) and prolonged contact with liquid nitrogen will cause frostbite. I probably don't need to tell you that the thousand degree muffle furnace is very hot and will burn you if you touch it, but I will.
Here are alternate instructions to make YBCO from Colorado Futuresciences.
© Copyright 2004 by Chris Heilman.