STARTSTART

What’s What’s “SUPER”“SUPER” about about SUPERCONDUCTORS?SUPERCONDUCTORS?

Clarina R. dela CruzHigh Pressure and Low Temperature

LaboratoryTexas Center for Superconductivity

University of Houston

metals wood

Conductors vs. InsulatorsConductors vs. Insulators

plastics

All electrons are PAIREDFREE ELECTRONS

What is Resistance?What is Resistance?

ELECTRIC FIELD VOLTAGE DIFFERENCE

IONS (+)

ELECTRONS (-)

conducto

rs

superco

nductors

Tccritical temperature

R=0

Zero resistance Zero power loss

BCS TheoryBCS Theory

John BardeenLeon CooperJohn Schrieffer(1957)

No collisions Zero resistance

The Meissner-Ochsenfeld EffectThe Meissner-Ochsenfeld Effect

Walter MeissnerRobert

Ochsenfeld (1933)

T>TCT<TC

Superconductor

Magnet

DIAMAGNETISMDIAMAGNETISM

?

Properties of a SuperconductorProperties of a Superconductor

•Zero resistance•diamagnetism

295 K,room temp

373 K,BP of water

273 K,FP of water

77 K,Liquid Nitrogen

4.2 K,Liquid Helium

Low -TLow -Tcc Superconductivity Superconductivity

Heike Kamerlingh Onnes

(1911)

LOW-tLOW-tC C Superconductors 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-THigh-Tc c SuperconductivitySuperconductivity

Alex Müller and Georg Bednorz

Paul Chu

164 K

295 K,room temp

373 K,BP of water

273 K,FP of water

77 K,Liquid Nitrogen

4.2 K,Liquid Helium

138 K,Highest Tc for HgBaCaCuO

ApplicationsApplications

What lies ahead?What lies ahead?

•Search for more efficient cryogenic cooling

•ROOM TEMPERATURE SUPERCONDUCTIVITY ?

REFERENCEShttp://superconductors.orghttp://www.lancs.ac.uk