Associated Faculty
Irinel Chiorescu
Eric Hellstrom
David Larbalestier
Theo Siegrist
Oscar Vafek
Research Examples
Overpressure furnace
This is an overpressure furnace that was purpose built to apply high temperature and pressure to heat treat Bi-2212, which is a high temperature superconductor. The combination of pressure (up to 50 bar), temperature (up to 900 °C), and oxygen partial pressure (1 bar) that we can achieve in this furnace squeezes bubbles out of the Bi-2212 superconductor. If these bubbles are present in the wire, they block the current flow, but when the furnace squeezes the bubbles out, the current significantly increases. Bi-2212 wire processed in this furnace can carry as much as 1000 A at 4.2 K in a 0.8 mm diameter wire. To get a sense of scale, a 0.8 mm diameter wire is only slightly larger than the lead in a 0.7 mm mechanical pencil. (The arrow corresponds to 1.4 m.)
Superconducting Bi-2212 filaments
This shows superconducting Bi-2212 (Bi2Sr2CaCu2O8) filaments in a wire that was prepared by overpressure processing. The filaments, which run the length of the wire, were exposed by etching away the Ag sheath. The SEM images begin at low magnification and show the microstructure of the Bi-2212 grains at increasing magnification. (M. Matras prepared the sample and did the SEM imaging, and P. Lee created the animation.)
