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START. What’s “SUPER” about SUPERCONDUCTORS?. Clarina R. dela Cruz High Pressure and Low Temperature Laboratory Texas Center for Superconductivity University of Houston. metals. wood. plastics. Conductors vs. Insulators. FREE ELECTRONS. All electrons are PAIRED. IONS (+)
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What’s “SUPER” about SUPERCONDUCTORS? Clarina R. dela Cruz High Pressure and Low Temperature Laboratory Texas Center for Superconductivity University of Houston
metals wood plastics Conductors vs. Insulators FREE ELECTRONS All electrons are PAIRED
IONS (+) ELECTRONS (-) VOLTAGE DIFFERENCE ELECTRIC FIELD What is Resistance?
conductors Tccritical temperature superconductors R=0 Zero resistance Zero power loss
BCS Theory Zero resistance No collisions John Bardeen Leon Cooper John Schrieffer (1957)
T>TC T<TC The Meissner-Ochsenfeld Effect Walter Meissner Robert Ochsenfeld (1933) ? Magnet Superconductor 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-tC 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 K4.15 K 1.175 K1.083 K0.915 K0.85 K0.61 K0.60 K0.517 K0.49 K0.40 K0.20 K0.128 K0.1125 K0.023 K 0.0154 K0.0019 K0.000325 K
Paul Chu Alex Müller and Georg Bednorz High-Tc Superconductivity 164 K
373 K,BP of water 295 K,room temp 273 K,FP of water 138 K,Highest Tc for HgBaCaCuO 77 K,Liquid Nitrogen 4.2 K,Liquid Helium
What lies ahead? • Search for more efficient cryogenic cooling • ROOM TEMPERATURE SUPERCONDUCTIVITY ?