Reprint: Making your own superconductor.

29 May 2020

Disclaimer: Times have changed since this article was written so seek legal and scientific advice from qualified personnel if you plan to try making your own superconducting materials.  I am not qualified personnel or a lawyer.  Do not try this at home.  We live in a world in which possession of basic chemistry apparatus is illegal in some places, so do your homework.

Process reprinted from OMNI Magazine, November 1987, page 76.  (local PDF) (local CBR) (right-click -> save as to download))

From How To Make Your Own Superconductors, by Bruce Schecter.  Retyped as faithfully as possible.  Hyperlinks mine, added for background.

Paul Grant, a research scientist at the IBM Almaden Research Center in San Jose, California, believes he has even come up with the first practice use of the new superconductors - science education.  A few months after he and his colleagues had whipped up their first batch, he advised high-school science teacher David Pribyl and his students from Gilroy, California (famous for its garlic), to have a go at making superconductors themselves.  Grant feels that this must be some kind of record.  "In less than six months a major discovery made the trip from the research laboratory to a high-school chemistry project," Grant says.  "Next year year, science fairs will have hundreds of these experiments."

The new superconductors are made up of yttrium, barium, copper, and oxygen - the chemical formula is Y1Ba2Cu3O7-x.  The proportions of the yttrium, barium, and copper have lead scientists to call this material 123 - a nice coincidence since making it is as easy as that.

To start, according to the recipe formulated by Grant, you will need some copper oxide, barium carbonate, and yttrium oxide.  The first two are often found in high school chemistry labs.  All three can be obtained from almost any chemical supply house or, as Grant suggests, scrounged from a nearby university or junior college.  The chemicals need not be that pure - 99.9 percent is fine.  As the formula implies, the proportions of the three chemicals should be one part yttrium to two parts barium to three parts copper.  According to Grant, 1.13 grams yttrium oxide, 3.95 grams barium carbonate, and 2.39 grams copper oxide will do just fine.

Grind the chemicals to a fine powder with a mortar and pestle, obtainable at any chemical warehouse.  Next bake the powders in a kiln at a temperature between 900°C and 950°C for 12 hours.  Turn off the kiln and, without removing the mixture, allow it to cool.  This should take five or six hours.  The resulting material should be a fragile black mass.  Grind it up again and place the powder in a disk-shaped die about a half inch in diameter.  Place a metal "anvil" (a piston that just fits in the die) over the powder and compress it in a hydraulic press to 15,000 to 18,000 pounds.  Such a hydraulic press is found in most high school machine shops.

The resulting disk is not yet a superconductor because, although it contains the right proportions of yttrium, barium, and copper, it does not contain enough oxygen.  The disk must be baked again, this time in a gentle flow of oxygen, which can be pumped back into the kiln with the sort of tube found in any chemistry lab.  (Adding oxygen isn't strictly necessary, but it makes for a better superconductor.)  The students at Gilroy High used oxygen obtained from their school's machine shop.  The material is again baked at 950°C, but it is crucial to cool it very slowly - eight hours at the minimum - to ensure it absorbs enough oxygen.

To make sure your project is successful you must be particularly careful about a few common pitfalls: Temperature is critical.  While baking your material at 950°C is ideal, cooking it at 1000°C often means failure.  You must make sure you cool your disk down slowly and measure your ingredients carefully.  Above all, keep your lab bench clean.  Contaminating one substance with another drastically lowers your chances of success.  Please remember, recipes are rarely complete.  The experienced chef knows this and fills in the missing steps unconsciously.  The same is true of laboratry recipes.  The consequences of mistakes in the kitchen are only unpalatable; laboratory mistakes can be dangerous or even deadly.  So have a professional, such as a science teacher, in the room while the work is being done.

But if all goes well, your disk will be a superconductor.  To prove this you will need some liquid nitrogen (which can be obtained from a local college, dermatologist, or welding supply house), an insulated cup, and a sliver of a samarium-cobalt magnet available from, among other sources, Edmund Scientific in Barrington, New Jersey.

Invert the insulated cup and place the disk of 123 on the slightly concave cup bottom.  Handle the 123 with plastic tweezers because it crumbles when it absorbs moisture.  Put a sliver of the magnet on top of the disk and pour on a little liquid nitrogen, just enough to almost submerge the disk.  As it cools , the 123 becomes furred with ice.  And then the magic: The disk becomes superconducting, and the magnet leaps into the air.

Already Arthur Ellis, of the chemistry department of the University of Wisconsin-Madison, plans to put together a levitation kit that includes a superconducting disk and magnet.  And as far as Grant is concerned, the specter of a magnet hanging in space should propel as many students into science as the ominous beeping of Sputnik did a generation ago.  "There will be kids growing up as familiar with superconductivity," he says, "as the present generation is with lasers and computers.  I don't want to oversell it, but it is to our benefit to have an electorate that is well educated in the science of the day."