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Why Do We Need Superconductors? And How Are The Made?

Why Do We Need Superconductors? And How Are The Made?. Developed from the talks of: Dr. Athena S. Sefat And Dr. Thomas Maier. This photo shows the Meissner effect, the expulsion of a magnetic field from a superconductor in super conducting state.

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Why Do We Need Superconductors? And How Are The Made?

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  1. Why Do We Need Superconductors? And How Are The Made? Developed from the talks of: Dr. Athena S. Sefat And Dr. Thomas Maier

  2. This photo shows the Meissner effect, the expulsion of a magnetic field from a superconductor in super conducting state. Image courtesy Argonne National Laboratory

  3. Why are we interested in Superconductors? • Power plants must increase their current to high voltages when transmitting it across country: to overcome energy lost due to resistance. Resistance is to electrons moving down a wire as rocks are in a stream. Imagine if we could find a way to remove resistance; • Energy in would equal Energy out • Energy Crisis Solved

  4. Whysuperconductors? • The Facts • Copper wire can carry 5 Amps/mm2 • Superconductors conduct electricity with significantly less resistance, but they must be cooled for the effect. • NbTi can carry 2500 Amps/mm2 • A “low temperature” superconductor because it must be cooled to 4.2 Kelvin using liquid Helium (very expensive) • YBCO can carry 10,000 Amps/mm2 • A “high temperature” superconductor because it must be cooled to 92 Kelvin using liquid Nitrogen (relatively inexpensive to produce) . Efficient/condensedunderground transmissionlines! ManagedbyUT-Battelle for theU.S. Departmentof Energy Compact,powerfulmotors/generators!

  5. Other PossibilitiesFromSuperconductors • https://www.youtube.com/watch?v=Z4XEQVnIFmQ

  6. Creating a Superconductor -Element Properties are important: reactivity,toxicity,generalproperties Tmelt(°C) metal radius(pm) Tboil(°C) D20°C(g/cm3)

  7. -Phase Diagrams Help to Target the Proper Elements Eutectic ptsCongruentreactionPeritectic reaction

  8. -The Secret Appears to be in the Crystalline Structure **Tetragonalstructures may be crucial **ThCr2Si2-type structure may be important One can explore other Fe-based compounds with this structure: ...

  9. -Preparation Methods are Critical Fe-based superconductor Cuprates B.R.Pamplin, Crystal Growth, Pergamonpress(1980).

  10. -Knowhowtoconfinereactions! Elements Container& tube choices Ta, steel Al2O3, MgO, BeO Alkali & alkaline-earthmetals Al, Ga MgO,Ta, graphite or steel graphite,MgO,Al2O3,Ta Al2O3, ZrO2 Al2O3 Al2O3,Ta Ta, Mo,W, BeO Al2O3, SiO2, graphite SiO2,graphite Mg Cu,Ag,Au Fe, Co, Ni Zn, Cd, Hg In Rare-earthmetals Bi, Sn Sb Tmax(°C) Tmelting(°C) platinum alumina(Al2O3) zirconia(ZrO2) 17203452 °F 1770 1900 2000 2072 2700 magnesia (MgO) tantalum 2400 1400 2852 3017

  11. SuperconductingMaterials have Complex Structures Normal Conductors Cu Fe Superconductors Ca Sr Ba T O Li orFe La AorB Y O Ba Hg R Ca 111, 11 AFeAs,FeSe TC ≈33, 15K 122 La-214La2CuO4TC= 40 K 1111 RFeAsOTC= 56 K Ba BFe2As2, AFe2Se2 TC≈38 K, 45 K 42622 Sr4T2O6Fe2As2 TC≈37 K Tl Y-123 Hg-1223 HgBa2Ca2Cu3O9+δ TC=133 K YBa2Cu3O7-δTC = 92 K Sefat, et al. MRSBulletin36(2011),614. Tl-2223 Tl2Ba2Ca2Cu3O10 TC = 125 K

  12. Example: LaAs+ x/3 Co3O4+ (3-4x)/9 Fe2O3+ (3-x)/9 Fe LaFe1-xCoxAsO Weighaccurately Sealintoa silica tube Heatstrongly e.g. 1220°C (2230 °F)!

  13. OurSuperconductivityResearch Aresearchworkflow ! 0 fc mm to cm χ(cm3/mol) zfc T(K) ρ(mOhmcm) wires 0 (b) Synthesis T(K) (a) Decision on a crystalstructure (c) Characterization

  14. The Science of Low Temperature Superconductors

  15. At Normal Temperatures Electrons in Conductors move independently Resistance within the conductor is due to the scattering. Low Temperature Superconductivity Tc

  16. Superconductivity is enabled by the Cooper danceCooper Pair Flash Mob

  17. Electrons form “Cooper” pairs. Cooper pairs synchronize electrons eliminating the scattering affect and removing resistance. Superconductivity = Cooper dance Tc

  18. e- e- But negative charges repel! So how can electron pairs form?

  19. Everything you wanted to know about pair formation … in low-temperature superconductors A lattice structure is formed as a part of the creation of the superconducting material. The first electron deforms the lattice of metal ions (ions shift their position due to Coulomb interaction) First electron moves away Second electron is attracted by lattice deformation and moves for former position of first electron e- + + e- e- + + e- + + + + + + + +

  20. Duplicating a Nobel Prize Winning Experiment

  21. LiquidHe Bardeen High temperaturenon-BCS Low temperature BCS Cooper Schrieffer HgTlBaCuO 1995 HgBaCaCuO 1993 140 ? Bednorzand Müller Temperature [K] TIBaCaCuO 1988 BCS Theory BiSrCaCuO 1988 100 • Low-temperature (conventional) superconductivity is a solved problem • We know that ion vibrations cause the electrons to pair • High-temperature superconductivity is an unsolvedproblem • We know that ion vibrations play no role in superconductivity • We don’t know (agree) what causes the electrons to pair YBa2Cu3O7 1987 Liquid N2 60 La2-xBaxCuO4 1986 MgB2 2001 20 NbC Nb3Ge V3Si Pb Nb3Su NbN Hg Nb 1940 1920 1960 1980 2000

  22. The Science of Low Temperature Superconductors is a SOLVED Problem High Temperature Superconductors are still Mysterious.

  23. Complexity in high-temperature superconducting cuprates • Low-temperature superconductors behave like normal metals above the transition (to superconductor) temperature • High-temperature superconductors display very strange behavior in their normal state • Stripes • Charge density waves • Spin density waves • Inhomogeneities • Nematic behavior • … • Many theories have been proposed,most of them are refuted by experiments “If one looks hard enough, one can find in the cuprates something that is reminiscent of almost any interesting phenomenon in solid state physics.” (Kivelson & Yao, Nature Mat. ’08)

  24. (Incomplete) list of theories for high-Tc Interlayer tunneling Marginal Fermi liquid Anyon superconductivity van Hove singularities Spin fluctuations Phil Anderson d-density wave SO(5) Alexei Abrikosov Resonating valence bonds Small q phonons Flux phases Excitons Stripes Charge fluctuations Interlayer Coulomb Bipolarons Tony Leggett BCS/BEC crossover Kinetic energy Bob Schrieffer Spin bags Orbital currents Plasmons Gossamer superconductivity Anisotropic phonons Spin liquids Bob Laughlin Karl Müller

  25. If we can solve Room Temperature Superconductors We can generate power from Solar Energy in the Deserts and use it anywhere. We can trim our energy budget while increasing our thirst for energy. Energy generation methods that are not viable become viable.

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