Synthesis

The superconductor synthesised in the ICL teaching lab's experiment is a non-stoichiometric mixed oxide of yttrium, barium and copper: YBa₂Cu₃0_x. The material is of current interest because it becomes superconducting when cooled to c.100K (i.e. above the boiling point of liquid nitrogen).

Here is a Quicktime movie of a superconductor's preparation in the ICL:

	Weigh out the ingredients and grind together thoroughly in a mortar.
	Transfer the mixture to an alumina crucible and place in the centre of a tube furnace. Pass a slow flow of oxygen over the mixture and bake at 350°C (662°F, Gas Mark: About 30 probably) for 1 hour. Then increase the temperature to 950°C (1742°F, Gas Mark: Very big indeed) and cook for a further 3 to 4 hours.
	Allow the furnace to cool somehwhat before removing the crucible with tongs and gloves. Let the crucible cool on a fire-brick before emptying the contents into the mortar. Re-grind thoroughly.
	Then press two 13mm pellets from the mixture (at 12 tons pressure).
	Place them in a crucible lined with platinum foil. An unlined crucible won't do since it would contaminate the pellet.
	Re-heat the crucible in the furnace to 950°C (1742°F, Gas Mark: Don't try this at home) with a slow flow of oxygen. Programme the furnace to cool the sample at 50°C/hour through the tetragonal-orthorhombic phase transition (at 690°C). Ensure an appropriate sign for an overnight reaction is displayed on your furnace and do remember to ask a Senior Demonstrator first!
	Switch off the tube furnace, allow to cool a little and then remove your sample as before.