START Whats SUPER about SUPERCONDUCTORS Clarina R dela

START

What’s “SUPER” about SUPERCONDUCTORS? Clarina R. dela Cruz High Pressure and Low Temperature Laboratory Texas Center for Superconductivity University of Houston

Conductors vs. Insulators FREE ELECTRONS metals All electrons are PAIRED wood plastics

IONS (+) What is Resistance? ELECTRONS (-) VOLTAGE DIFFERENCE ELECTRIC FIELD

rs cto du n o c s or t Tc critical temperature uc d n o rc e p su R=0 Zero resistance Zero power loss

BCS Theory No collisions Zero resistance John Bardeen Leon Cooper John Schrieffer (1957)

The Meissner-Ochsenfeld Effect Walter Meissner Robert Ochsenfeld (1933) Magnet ? Superconductor T>T T<TC DIAMAGNETISM

Properties of a Superconductor • Zero resistance • diamagnetism

373 K, BP of water 295 K, room temp 273 K, FP of water 77 K, Liquid Nitrogen 4. 2 K, Liquid Helium

Low -Tc Superconductivity Heike Kamerlingh Onnes (1911)

LOW-t. C Superconductors Lead (Pb) Mercury (Hg) Aluminum (Al) Gallium (Ga) Molybdenum (Mo) Zinc (Zn) Zirconium (Zr) Americium (Am) Cadmium (Cd) Ruthenium (Ru) Titanium (Ti) Uranium (U) Hafnium (Hf) Iridium (Ir) Beryllium (Be) Tungsten (W) Platinum (Pt)* Rhodium (Rh) 7. 196 K 4. 15 K 1. 175 K 1. 083 K 0. 915 K 0. 85 K 0. 61 K 0. 60 K 0. 517 K 0. 49 K 0. 40 K 0. 20 K 0. 128 K 0. 1125 K 0. 023 K 0. 0154 K 0. 0019 K 0. 000325 K

High-Tc Superconductivity 164 K Paul Chu Alex Müller and Georg Bednorz

373 K, BP of water 295 K, room temp 273 K, FP of water 138 K, Highest Tc for Hg. Ba. Cu. O 77 K, Liquid Nitrogen 4. 2 K, Liquid Helium

Applications

What lies ahead? • Search for more efficient cryogenic cooling • ROOM TEMPERATURE SUPERCONDUCTIVITY ?

REFERENCES http: //superconductors. org http: //www. lancs. ac. uk