1. Overview and Application of Superconducting Materials CHEN 313: Materials Group 11 Raul Calzada Chris Gibson Tasnim Mohamed Patty Soong Papers Used: Overview of Superconductivity and Challenges in Applications Entangling Superconductivity and Antiferromagnetism Review on Superconductivity: The Phenomenon Occurred at Low Temperature 100 Years of Superconductivity and 50 Years of Superconducting Magnets Superconductors Beyond 1-2-3 Superconducting Properties of Ag and Sb Substitution on Low-Density YBa 2 Cu 3 O x Superconductor Fundamentals of Materials Science and Engineering: Magnetic Properties http://ocw.mit.edu/ans7870/8/8.02T/f04/visualizations/farada y/16-superconductor/16-12_wmv320.html

2. Callister, W.D. 2012, 776-779. http://lrrpublic.cli.det.nsw.edu.au/lrrS ecure/Sites/Web/physics_explorer/ph ysics/lo/superc_05/superc_05_02.ht m Cava, J.R. Sci. Amer. 1990. http://www.magnet.fsu.edu/education/tutorial s/magnetacademy/mri/ http://science.nasa.gov/science-news/science- at-nasa/2003/05feb_superconductor/ http://science.nasa.gov/science- news/science-at- nasa/2003/05feb_superconductor/ http://en.wikipedia.org/wiki/Meissner_effect Electromagnetic Practical Structure State Superconducting materials have electromagentic properties, a unique structure, are in a special state of matter, and will have practical applications in the future

3. Helium liquefier completed in 1908 in Leiden Superconductivity first observed in 1911 by Kamerlingh Onnes Meissner effect discovered in 1933 First superconducting magnet made in 1954 by George Ynetma Yttrium Barium Copper Oxide superconductor with a transition temperature of 90 K developed in 1987 Figure 3.1: Kamerlingh Onnes (left) and Van der Waals (right) with the Leiden helium liquefier. https://commons.wikimedia.org/wiki/File:Heik e_Kamerlingh_Onnes_and_Johannes_Dideri k_van_der_Waals.jpg Figure 3.2: Walther Meissner, the discoverer of damping of the magnetic field in superconductors (Meissner effect) http://en.wikipedia.org/wiki/Walther_Meissner Callister, W.D. 2012, 776-779 Wilson, N.W.; IEEE Trans. Appl. Supercond. 2012, 22, 3. Introduction

4. Superconductivity is a state of thermodynamical equilibrium that affects a material's electric and magnetic properties. Superconductivity arises from an attractive interaction between pairs of conducting electrons, and their interaction with lattice vibrations* It can be achieved by lowering the material temperature below its critical temperature *The advanced theory behind superconductivity is beyond the scope of the presentation http://hyperphysics.phy- astr.gsu.edu/hbase/soli ds/coop.html http://wikis.lib.ncsu.edu/index.php/ Magnetic_Levitation_with_Superco nductors Flukiger, R. Rev. Accel. Sci. Tech. 2012, 5, 1-23. F igure 4.2: Cooper pair illustrating energy exchange through phonon interaction. F igure 4.1: Illustration of cooper pairs moving through a lattice. Cooper pair movement is thought to be the reason superconductivity occurs.

5. In 1957, Bardeen, Cooper, and Schrieffer (BCS) theorized that superconductivity was the result of electrons binding to form particles called Cooper pairs The electrons exchange vibrational lattice energy called phonons which can result in the electrons becoming attracted to one another Recently, antiferromagnetism has been linked to the explanation of high temperature ceramic superconductivity By changing the chemical composition, BaFe 2 (As 1-x P x ) 2 has been observed to have an internal magnetic critical point As the composition is changed, antiferromagnetism decreases until it disappears, resulting in superconductivity Figure 5.1: (Top) Lattice of an antiferromagnet. The electron spins are antiparallel, leading to cancellation of the magnetic field. (Bottom) Cooper pair formation. Electrons bind during superconductivity and create boson particles called Cooper pairs. Sachdev, S. Science. 2012, 336, 1510-1511. Sachdev, S. Science. 2012, 336, 1510-1511. Basic Principles

6. Below a critical temperature (T c ), the resistance of a superconducting material becomes almost zero causing current to flow indefinitely and with no power loss No voltage difference is needed to maintain a current. Above a current density, superconductivity is lost in the material. A supercurrent can flow across an insulating junction in what is called the Josephson Effect. Cooper pairs can do this due to quantum tunneling Figure 6.1: Critical temperature, current density, and magnetic field boundary separating superconducting and normal conducting states. Superconductivity can only occur within the teardrop figure. http://hyperphysics.phy-astr.gsu.edu/hbase/solids/squid.html Callister, W.D. 2012, 776-779. Flukiger, R. Rev. Accel. Sci. Tech. 2012, 5, 1-23. Patel, M.J. et. al. Nat. Confer. Rec. Trend. Engr. Tech. 2011. Sachdev, S. Science. 2012, 336, 1510-1511 Figure 6.2: Schematic of the Josephson Effect; this effect allows electrons to jump through insulators

7. Superconductors can be classified into two types according to their interaction with an external magnetic field: Type I Type I superconductors expel all magnetic flux Superconductivity ends when a critical flux is applied. Examples include mercury, lead, and tin. http://www.gitam.edu/eresource/Engg_Phys/semester_2/supercon/type_1_2.ht m Callister, W.D. 2012, 776-779. Patel, M.J. et. al. Nat. Confer. Rec. Trend. Engr. Tech. 2011. Figure 7.1: Type I superconductors are different than Type II superconductors. This figure shows the comparison of graphs Bc vs Tc in both types. Type II has a mixed state while Type I does not.

8. Type II Type II superconductors, unlike type I, have two critical fields. After the first critical field is reached, magnetic flux partially penetrates the material and it enters a state of mixed normal and superconductivity. After the second critical flux is passed, superconductivity abruptly ends. Type II superconductors usually have higher critical temperatures. Examples include YBCO, vanadium, and BSCCO http://es.wikipedia.org/wiki/Superconductor_de_tipo_II Figure 8.1: Graph illustrating magnetization versus magnetic field strength. Type I is red and Type II is blue. If an external magnetic field is applied, Type II's field gradually declines while Type I has a sharp drop off. This demonstrates a significant difference between the types. Callister, W.D. 2012, 776-779. Patel, M.J. et. al. Nat. Confer. Rec. Trend. Engr. Tech. 2011.

9. Fig 9.1: Comparison of superconductor and standard conductor in a magnetic field. The superconductor excludes itself from the field while the field passes through the conductor. Superconductor Conductor The phenomena of expelling magnetic flux experienced by superconductors is called the Meissner Effect. The Meissner Effect can be understood as perfect diamagnetism, where the magnetic moment of the material cancels the external field or M = - H. The critical field and temperature are interdependent through: B c = B 0 [1-(T/T c ) 2 ] This is observed in Type I superconductors, but it can also be used to approximate the behavior of Type II Callister, W.D. 2012, 776-779. Flukiger, R. Rev. Accel. Sci. Tech. 2012, 5, 1-23. Patel, M.J. et. al. Nat. Confer. Rec. Trend. Engr. Tech. 2011. Callister, W.D. 2012, 776-779.

10. The strange magnetic properties created by superconductors can cause the material to levitate in place over a magnet The superconductor will remain a certain distance from the magnet but will not flip over or reorient This video demonstrates this phenomena and potential for levitation applications http://www.youtube.com/watch?v=6lmtbLu5nxw

11. Table 11.1: Critical Temperatures of Conducting Materials In most metals such as titanium, copper, or lead, resistivity decreases as temperature decreases However, the resistivity suddenly drops to near zero at a critical temperature (T c ) Metals and metal alloys have a critical temperature of less than about 20 K, which is extremely low and difficult to achieve. Yttrium Barium Copper Oxide (YBCO) has a critical temperature of 92 K and others are even higher. These temperatures can be achieved by utilizing liquid nitrogen, a relatively cheap coolant. F igure adapted from Callister, W.D. 2012, 776-779. Material Critical Temperature Critical Magnetic Flux Tc (K) Bc (tesla)

12. Some metals become superconductors at extremely low temperatures Some of these include mercury, lead, tin, aluminum, lead, niobium, cadmium, gallium, zinc, and zirconium Unfortunately, the critical temperatures are too low for practical application For example, Aluminum has a T c of only 1.20K, nearly impossible to reach by conventional methods Fig. 12.1: Aluminum tubing can become superconductive at very low temperatures. http://www.globalmetals.com/aluminum- tubestubing.htmlttp://www.globalmetals.com/aluminum- tubestubing.html Fig. 12.2: Lead can also become superconductive at low temperatures. http://39clues.wikia.com/wiki/Lead http://39clues.wikia.com/wiki/Lead Patel, M.J. et. al. Nat. Confer. Rec. Trend. Engr. Tech. 2011.

13. Metal alloys like Nb-Ti, and Nb-Zr are usually Type II superconductors Metal Alloys have higher critical temperatures and magnetic fluxes than pure metals. As a consequence of their properties, they are more useful for practical applications than pure metals http://www.intechopen.com/books/applications-of-high-tc-superconductivity/superhard- superconductive-composite-materials-obtained-by-high-pressure-high-temperature- sintering Patel, M.J. et. al. Nat. Confer. Rec. Trend. Engr. Tech. 2011. Fig 13.1: Lattice structure of Nb-Ti metal alloy. The different composition allows the Tc to be higher than metals.

14. Yttrium Barium Copper Oxide was the first superconductor developed with a T c above the boiling point of Nitrogen (T c =90 K). Thallium Barium Calcium Copper Oxide has the highest T c out of all superconductors (T c =125 K) Copper Oxides are believed to be good superconductors partly due to the Jahn- Teller effect, which causes the 2 oxygens on opposite sites of the octahedron to be farther from the copper than the other 4 oxygens of the octahedron. This suggests that the electrons interact strongly with the positions of copper and oxygen in the lattice (Cooper pair). Antiferromagnetism must be eliminated for superconductivity to appear. Copper Iron http://www.chemistryexplained.com/St-Te/Superconductors.html Cava, J.R. Sci. Amer. 1990. Figure 14.1 (top): Illustration of a ceramic lattice. The Jahn-Teller effect causes the superconductivity here. Figure 14.2 (bottom): Levitation caused by the interactions of electrons and oxygen, and therefore superconductivity.

15. Fig 15.1: Other copper oxides that are also superconducting. These ceramics show potential for applications. For industrial setting, the toxicity of the materials should be considered. Cava, J.R. Sci. Amer. 1990.

16. Figure 16.1: As time continues, superconductors with higher T c values are being developed and discovered. The trend moves upward. Flukiger, R. Rev. Accel. Sci. Tech. 2012, 5, 1-23. (modified)

17. Different concentrations of Silver (Ag) and Lead (Sb) were introduced as impurities into a YBCO ceramic compound It was found that the addition of Ag at an optimum concentration enhanced both the critical temperature and current density of YBCO. Above and below this concentration the properties diminished Sb impurities did not affect the superconducting properties of the YBCO ceramic. As impurities of Ag and Pb were added to YBCO, the transition temperature range, delta Tc was affected The correlation between concentration of Ag or Pb versus transition temperature difference appeared to be random Azhan, F.; et al. J. Supercond. Nov. Magn. 2013, 26, 921-935. http://www.kreynet.de/asc/ybco.html Silver (Ag) Lead (Pb) http://www.galleries.com/Lea d http://www.hobart.k1 2.in.us/ksms/Periodi cTable/antimony.ht m Figure 17.1: Adding Ag and Pb impurities to the lattice structure of YBCO can alter its superconductive properties slightly.

18. Azhan, F.; et al. J. Supercond. Nov. Magn. 2013, 26, 921-935. Fig 18.1: The onset temperature is the upper range of the transition range. The zero temperature is the lower range. The table shows the varying effect of adding impurities in the YBCO on the transition temperature range.

19. Azhan, F.; et al. J. Supercond. Nov. Magn. 2013, 26, 921-935. From the work, the transition temperature range of YBCO can be controlled using impurities of metals This experiment was useful because it shows that adding impurities to YBCO can alter its T c and J c values slightly This may be helpful for figuring out new ceramic superconductors. For example, another experiment could be adding gold or platinum impurities to YBCO to see its effect on its superconductive properties This experiment will also help elucidate the molecular working of superconducting materials by showing different crystals structures were superconduction occurs. http://commons.wikimedia.org/wiki/File:YBCO-3D-balls.png Figure 19.1: Lattice structure of YBCO showing its complexity. In this experiment, YBCO was modified to test its properties.

20. Superconductors have potential to create a new variety of electrical and magnetic technologies Superconductors will need to be improved by researching and synthesizing a ceramic superconductor with a high critical temperature value By doing this, either minimum cooling, or no cooling at all would be needed to create superconductive properties in the material For example, YBCO only requires liquid nitrogen for cooling. Conventional freezers could be used if the T c could be increased to around 190 K Since superconductors can be applied without solid understanding of the theory behind it, they are an attractive material HgBa 2 Ca 2 Cu 3 O x Figure 20.1: Applied Magnetic Field vs Critical Temperature. As the critical temperature increases, the applied magnetic field decreases. http://www.imagesco.com/articles/superconduct ors/determining-critical-magnetic-field.html http://www.imagesco.com/articles/superconduct ors/determining-critical-magnetic-field.html (modified) Flukiger, R. Rev. Accel. Sci. Tech. 2012, 5, 1-23. Patel, M.J. et. al. Nat. Confer. Rec. Trend. Engr. Tech. 2011.

21. If a high critical temperature superconductor is developed that has a critical temperature that is higher than HBCCO (133 K), more practical applications will become feasible Electrical power transmission through superconducting materials and wire o Low power loss o Low voltage required for high current o Utilizes less physical space Computer signal transmission o Low resistivity allows for computing speed to increase greatly http://gigaom.com/2010/10/06/superconducting-wire-powering-up-korean-smart-grid/ http://nextbigfuture.com/2009/12/cost-and-benefits-of-2g-superconducting.html Callister, W.D. 2012, 776-779. Flukiger, R. Rev. Accel. Sci. Tech. 2012, 5, 1-23. Figure 21.1,2: Power lines demonstrating the great reduction of space needed by utilizing superconducting wire rather than standard cables.

22. http://gigaom.com/2010/10/06/superconducting-wire-powering-up-korean-smart-grid/ Figure 22.1: Example of a superconducting cable. The liquid nitrogen coolant is part of the cable in order to keep the superconductor wire below the critical temperature. These cables can greatly reduce the physical space needed in our electrical infrastructure. Callister, W.D. 2012, 776-779. Flukiger, R. Rev. Accel. Sci. Tech. 2012, 5, 1-23.

23. Some applications are used today: o Magnetic Resonance Imaging o Nuclear Magnetic Resonance Spectroscopy Future applications can benefit from interesting magnetic properties displayed by superconductors Particle Accelerators Magnetic Levitation o High-Speed Magnetic Levitation Trains for mass transport o By utilizing levitation, friction between the train and the track is eliminated o This can allow trains to increase their speed dramatically http://science.nasa.gov/science-news/science-at-nasa/2003/05feb_superconductor/ http://www.cis.rit.edu/class/schp730/lect/lect-17.htm http://www.magnet.fsu.edu/educatio n/tutorials/magnetacademy/mri/fullart icle.html Callister, W.D. 2012, 776-779. Flukiger, R. Rev. Accel. Sci. Tech. 2012, 5, 1-23. Patel, M.J. et. al. Nat. Confer. Rec. Trend. Engr. Tech. 2011. Figure 23.1,2 (top/middle): MRI scanners currently utilize superconductors. Figure 23.3 (bottom): Mag-Lev train demonstrating the potential of using superconductors in mass-transport.

24. Superconductivity is a state of thermodynamical equilibrium where the electrical resistance is 0 and that is achieved at near 0 K temperatures External magnetic flux is expelled from the superconductor in what is called the Meissner effect. The application of an external magnetic flux also lowers the critical temperature at which superconductivity is achieved. After a critical flux, superconductivity can no longer be achieved Using superconducting materials in circuit elements would mean zero power loss due to resistance. Also, no voltage difference would be needed to maintain the current. Adding impurities to ceramic superconductors can alter the critical temperature and critical current density Superconducting ceramic materials have shown the most promise for future technologies because of their relatively high critical temperatures The underlying principles of superconductivity are explained through an interactive attraction between electrons (Cooper pair) and their interaction with lattice vibrations (phonons). Figure 24.1: Structural interpretation of a ceramic superconductor. Notice how there are layers of molecules sandwiched between others. http://physics.aps.org/story/v9/st12

25. Azhan, F.; Fariesha, F.; Yusainee, S. Y. S.; Azman, K.; Khalida, S.; Superconducting Properties of Ag and Sb Substitution on Low-Density YBa 2 Cu 3 O δ Superconductor. J Supercond Nov Magn. 2013, 26, 921-935. Callister, W.D.; Rethwisch, D.G. Fundamentals of Materials Science and Engineering. John Wiley & Sons, Inc. 2012, Magnetic Properties, p776-779. Cava, J.R.; Superconductors and beyond 1-2-3. Scientific American 1990. Flukiger, R. Overview of Superconductivity and Challenges in Applications. Reviews of Accelerator Science and Technology. 2012, 5, 1-23. Patel, M.J.; Agrawal, D.H.; Pathan, A.M. Review on Superconductivity: The Phenomenon Occurred at Low Temperature. National Conferences on Recent Trends in Engineering & Technology. 2011. Sachdev, S. Entangling Superconductivity and Antiferromagnetism. Science. 2012, 336, 1510-1511. Wilson, N.W. 100 Years of Superconductivity and 50 Years of Superconducting Magnets. IEEE Transactions on Applied Superconductivity. 2012, 22, 3.