Bulk (RE)BCO Superconductors; Science, Technology and Applications David Cardwell

Size: px

Start display at page:

Download "Bulk (RE)BCO Superconductors; Science, Technology and Applications David Cardwell"

Shavonne Blair
5 years ago
Views:

1 Bulk (RE)BCO Superconductors; Science, Technology and Applications David Cardwell Department of Engineering, University of Cambridge ESAS Summer school, Bologna, 8-14 June, 2016 Bulk Superconductivity Group Group Members: University Lecturer; Dr John Durrell SRA; Dr Yunhua Shi RA; Dr Devendra Kumar, Dr Difan Zhou Professor Archie Campbell (Emeritus) Royal Academy of Engineering Fellow; Dr Mark Ainslie PhD Students; Wei Zhai, Jin Zou, Di Hu, Kysen Palmer, Wen Zhao, Jordan Rush Technical Officer; Tony Dennis Technician; Danny Huang Plus Masters students, 4th year project students and visitors 2 1

Bulk Superconductivity Group Group Members: University Lecturer; Dr John Durrell SRA; Dr Yunhua Shi RA; Dr Devendra Kumar, Dr Difan Zhou Professor Archie Campbell (Emeritus) Royal Academy of

2 Bulk Superconductivity Group Group Members: University Lecturer; Dr John Durrell SRA; Dr Yunhua Shi RA; Dr Devendra Kumar, Dr Difan Zhou Professor Archie Campbell (Emeritus) Royal Academy of Engineering Fellow; Dr Mark Ainslie PhD Students; Wei Zhai, Jin Zou, Di Hu, Kysen Palmer, Wen Zhao, Jordan Rush, Jasmin Congreve Technical Officer; Tony Dennis Technician; Danny Huang Plus Masters students, 4th year project students and visitors 3 4 Cambridge Bulk Superconductivity Group 2

3 Bulk Superconductivity Group Principle Collaborators: Atomic Institute, TU Vienna IFW, Dresden Brunel University (Dr Hari Babu) University of Oxford University of Liege Shanghai Jiatong, Beijing and Shannxi Universities Boeing Siemens KACST (Riyadh) Florida State University (NHFML) 5 Overview Introduction General properties of bulk superconductors Practical TSMG processing method for bulk (RE)BCO Nano-scale second phase inclusions Generic seed Multi-seeding Infiltration and growth Record fields Conclusions and summary 6 3

General properties of bulk superconductors Bulk Type II high temperature superconductors have significant potential for high magnetic field applications at 77

trap significantly greater magnetic fields than can be generated by permanent magnets (limited to < 1.

4 General properties of bulk superconductors Bulk Type II high temperature superconductors have significant potential for high magnetic field applications at 77 K M. Murakami, SUST, General properties of bulk superconductors Potential for high magnetic field applications at 77 K is based on their ability to trap significantly greater magnetic fields than can be generated by permanent magnets (limited to < 1.8 T in iron) Candidate materials must pin magnetic flux effectively and hence be able to carry high critical current densities, Jc s, over large length scales and be insensitive to the application of magnetic fields 4

5 General properties of bulk superconductors Field generated by induced macroscopic currents rather than spins. Magnetic moment = ò i da da i The bigger the current loop, the bigger its magnetic moment Magnetisation increases with sample volume BIG samples carrying large currents = BIG fields 9 Field generation by Type II superconductors Eddy currents induced by external magnetic field Eddy currents initially flow on surface superconductors to maintain zero internal field below Bc1 (Meissner state) Field penetrates the sample for applied field above B c1 Both surface and bulk currents contribute to field generated by the superconductor Flux is quantised! 10 5

6 Faraday s lines of force N S Magnet0873.png, Wikipedia 11 Flux quantisation Magnetic flux penetrates a type II superconductor in the form of flux quanta of magnitude j = h 2e (2 x Wb) Flux lines in NbSe2, University of Oslo 12 6

The Lorentz Force Flux lines in a Type II superconductor carrying a current experience a Lorentz F = J ^ B per unit volume B Flux lines move when Lorentz force exceeds any pinning force J Dissipation

7 The Lorentz Force Flux lines in a Type II superconductor carrying a current experience a Lorentz F = J ^ B per unit volume B Flux lines move when Lorentz force exceeds any pinning force J Dissipation Need to pin flux lines 13 M-H Loop m 0M Irreversibility field (Lorentz force exceeds pinning force) B Current flows where field penetrates the superconductor (Bean model) Sample fully penetrated Width of hysteresis is proportional to Jc 7

Irreversibility field (T) Irreversibility 14 Tl-1223 Bi-2223 12 NdBCO YBCO Bi-2212 10 8 H c2 6 Lq.

8 Irreversibility field (T) Irreversibility 14 Tl-1223 Bi NdBCO YBCO Bi H c2 6 Lq. N2 YBCO Reduced Temperature (T/Tc) 15 Granularity is a problem! Sintered YBCO 2 µm 16 8

in the form of large grains (i.e. no grain boundaries).

9 Candidate Materials YBa2Cu3O7-d YBCO 92 K GdBa2Cu3O7-d GdBCO 92 K Sm1+xBa2-xCu3O7-d SmBCO 92 K Nd1+xBa2-xCu3O7-d NdBCO 94 K YBCO has greatest short-term potential for applications, provided in can be made in the form of large grains (i.e. no grain boundaries). GdBCO looking good for large scale applications 17 Flux profile tml B = m x 0 Jc Maximise Jc x d product YBCO; 20 mm diameter University of Cambridge 9

pairs Reduction in energy of Cooper pairs is the thermodynamic driver of

10 Aside: BCS Theory 1957 Quantum mechanical phenomenon, described in momentum space Condensation of electrons (Fermions) into a single (Boson) state by forming Cooper pairs Reduction in energy of Cooper pairs is the thermodynamic driver of superconductivity focus.aps.org www-linux.gsi.de Cooper pairs! Cooper Pears print by Alison Cooper,

11 BCS Theory BCS theory is extremely successful BUT, theory predicts; Tc = 1.14 q D exp 1 U D(e f) Maximum Tc of around 28 K (NbGe3, discovered 1975) BaPb1-xBixO3 unexplained (Tc = 13 K, discovered 1976) A lesson for life! A design weight of greater than 1.1 lb/hp will never be achieved using a gas turbine (jet) engine. Propeller driven engines are the only practical option for long-term aircraft propulsion (Unattributed) statement in 1940 by representative of U. S. aeronautical industry following exhaustive study of propulsion Fortunately, I Sir Frank Whittle was too stupid to know 11

12 A lesson for life! Bednorz and Müller, Zeitscrift für Physik B 64, (1986) Back to large grain (RE)BCO! 24 12

13 Seeded melt growth All (RE)BCO melt processes are based on the following peritectic reaction that occurs around 1015 C: 2(RE)Ba2Cu3O7-d (123) (RE)2BaCuO5 + (Ba3Cu5O8) (211/422) Liquid Structurally compatible seed with higher melting point usually used to seed large grain growth in top seeded melt growth process (TSMG). E.g. Tp(SmBCO) ~ 1070 C, Tp(YBCO) 1015 C 25 Peritectic Solidification Seed HOT COLD Process under a thermal gradient and enrich starting composition with up to 40 mol % excess Y-211or Y2O3 and 0.1 wt% Pt; YBa2Cu3O7-d + Y2BaCuO5 + Pt Y2BaCuO5 + L 13

(RE)BCO Bulk Microstructure Discrete Y-211 particles, typically of size around 1 m m embedded in a bulk superconducting Y-123 matrix 27 (RE)BCO Bulk Microstructure Homogeneous distribution of fine,

14 (RE)BCO Bulk Microstructure Discrete Y-211 particles, typically of size around 1 m m embedded in a bulk superconducting Y-123 matrix 27 (RE)BCO Bulk Microstructure Homogeneous distribution of fine, second phase particles correlates with increased flux pinning and hence increased Jc Murakami, Supercond. Sci. Technol., Jc (Acm ) Y-211 inclusions not necessarily optimum for flux pinning Y-211 Volume Fraction per cm 28 14

The challenge To fabricate large, single grain, (RE)BCO bulk superconductors by a practical melt process with efficient flux pinning, high critical

15 The challenge To fabricate large, single grain, (RE)BCO bulk superconductors by a practical melt process with efficient flux pinning, high critical current density and high trapped fields. 29 Three key developments in bulk processing Nano-scale second phase inclusions Generic seed Multi-seeding 30 15

16 New Flux Pinning Phase Novel pinning centres the 2411 phase (RE)2Ba4CuMOy RE = Sm, Gd, Nd, Y M = Nb, Zr, Hf, W, Bi, Ag, U etc. All paramagnetic and non-superconducting down to 5 K 32 16

17 Novel pinning centres the 2411 phase 33 Novel pinning centres the 2411 phase > 30 known 2411 compositions 34 17

18 nanocomposites Y2Ba4CuRuOy Y2Ba4CuTaOy 500 nm 200 nm a/b Y2Ba4CuWOy Y2Ba4CuWOy Y-211 Y2Ba4CuHfOy 10 m 2m m Durham, 08 February, Flux pinning - YBCO containing Y-2411 (Nb) 2411 content has a significant effect on Jc 6 wt % of Y-2411gives optimum performance 36 18

19 Generic Seed Crystal Generic seeds RE in (RE)Ba2Cu3O7 MgNdBCO La Nd Sm Eu Gd Dy Ho Y Er Yb Melting point (±5 oc) Requirements; 1. Higher melting point 2. Chemical compatibility 3. Structural compatibility 38 19

20 Generic seeds higher melting point DTA (arbitrary values) 5 Tp 0 Mg-doped NdBCO has at least 15 oc higher melting point than any other (RE)BCO. NdBCO containing 1 wt% MgO melt processed crystal (Lu, Yb, Y Tm, Er, Ho) Shi et al, Supercond. Sci. Technol., 2005 Gd EuSm Nd La o T( C) Generic seeds lattice matching Nd % Nd wt% MgO (melt processed) Nd-422 MgO Mg-doped NdBCO crystal structure is similar to that of NdBCO Lattice mismatch is negligible (~ 0.7% ) (Nd-123) 40 20

21 Generic seeds versatility (a) (b) (c) Photographs of (a) YBCO single grain (20 mm dia without 2411) (b) YBCO with 2411 and (c) GdBCO single grain (26 mm dia) with All samples were grown in air using the generic seed. 41 Multi-seeding 21

22 Multi-seeding Multi-seeding has the potential to; 1. Increase overall grain size (and hence Jc x d) 2. Enable the fabrication of conformal geometries 3. Yield strongly-connected grain boundaries 4. Reduce the level of impurities 43 Multi-seeding bridge seeds d = 3 mm d=9 mm 4 GBs with 5 nuclei d = 11 mm 44 22

23 Multi-seeding bridge seeds d = 0.5 d = 1.0 d = Multi-seeding oriented seed growth in YBCO Y Axis Title Y Axis Title X Axis Title X Axis Title # T # T Shi et al, Supercond. Sci. Technol., 26,

47 Multi-seeding oriented 4 seed growth in YBCO 20120606-TF -0.07800 20 0.

24 Multi-seeding oriented seed growth in YBCO Shi et al, Supercond. Sci. Technol., 26, Multi-seeding oriented 4 seed growth in YBCO TF Y Axis Title mm Pair X Axis Title # T 48 24

25 Buffer-aided Top Seeded Infiltration and Growth process Limitations of TSMG Porosity and macro-cracks Occurrence of RE-211free regions Shrinkage Devendra et al. J. Eur. Ceram. Soc (2016) 25

26 Top seeded Infiltration Growth process Y2BaCuO5 + LP (BaCuO2+CuO) YBa2Cu3O7-x Advantages TSMG TSIG Kumar et al Nova Science Publishers. ISBN: p.1-35 (2015) TSMG TSIG Buffer pellets and their advantages Buffer pellet absorbs all the defects occurring due to lattice mis-match effects of seed-(re)bco Enables reliable growth of single grains. N. Devendra Kumar et al. Cryst. Growth Des. 15 (2015)

27 Microstructural study BA-TSIG Y-211 content: % Devendra et al. Supercond. Sci. Technol (2016) Superconducting properties in TSIG processed YBCO 77 K 27

28 Reliability of TSIG processing - YBCO bulks Recycling of YBCO bulks via BA TSIG Shi et al. J. Amer. Ceram. Soc (2015) 28

29 Quasi-single grain of TSIG - YBCO via Multiseeding Shi et al. (to be published) Record Trapped Fields 29

High Field Measurements on Cambridge Samples Collaboration with FSU to use

30 Record trapped fields (RE)BCO Tomita and Murakami, Nature, 421, 517, 2003 YBCO Double sample arrangement Record until recently was 17 T at 29 K 59 High Field Measurements on Cambridge Samples Collaboration with FSU to use NHMFL facilities 20 T SC Magnet Can our Bulk Superconductors trap record fields? 60 30

31 They can!! 61 Record trapped fields in (RE)BCO at Cambridge 2 samples combined with hall probes set in the centre. Mounted top surface to top surface. GdBCO sample 10 mm Stainless Steel Reinforcement Ring Collaborative study with NHFML and Boeing 62 31

32 Record trapped fields in (RE)BCO at Cambridge Durrell et al, Superconductor Science and Technology, 27, , 2014 Measured Field (T) 20 Trapped Field 17.6 T 15-8 mm (T) -4 mm (T) 0 mm (T) 4 mm (T) 8mm (T) Small sample (24 mm diameter) 26 K Energy density > 25 MJ/m3 Equivalent to 12% of energy density of TNT! 15 Applied Field (T) 63 Record trapped fields in (RE)BCO at Cambridge Durrell et al, Superconductor Science and Technology, 27, , Field at centre (T) 15 Field of almost 10 T at centre of sample at 50 K 10 5 (a) Sample Temperature (K) 64 32

33 Record trapped fields in (RE)BCO at Cambridge Durrell et al, Superconductor Science and Technology, 27, , T 26 K (end of ramp) 26 K (after h) 35 K 45 K 50 K 20 Field flattens-off at low temperature Suggests not sample limited Field (T) (b) Distance (mm) K Field Measured at Centre of Sample (T) Field (T) Practical trapped field in (RE)BCO Single sample Distance from centre of sample Temperature (K) Unreinforced GdBCO 20 mm diameter traps ~7 T at 50 K Has to be warmed to 50 K before reduction in trapped field is seen Can reproducibly achieve 7 T performance at 50 K 66 33

2015 Article made open access with HEFCE funds, free

34 Press Coverage Press Coverage Paper has been downloaded > 3000 times since July 2014 Most cited SUST paper in 2015 Article made open access with HEFCE funds, free for all to download Significant traffic to UCAM website 34

35 Applications of Bulk Superconductors 1. Magnetic bearings Maglev (low loss) Flywheel energy storage 2. Motors and generators Higher efficiency, lower loss, smaller machines 3. Medical device applications Drug delivery, MRI 4. Other applications Applications of Bulk Superconductors 1. Magnetic bearings Maglev (low loss) Flywheel energy storage 2. Motors and generators Higher efficiency, lower loss, smaller machines 3. Medical device applications Drug delivery, MRI 4. Other applications 35

Levitation Devices (Maglev) The first people

passengers over a distance of around 500 km

36 Levitation Devices (Maglev) The first people carrier levitated by bulk superconductors 635 kg levitation capability 198 kg lateral restorable 20 mm Carried over 40,000 passengers over a distance of around 500 km Southwest Jiatong University, PR China Cryostat for Maglev 36

37 Applications of Bulk Superconductors 1. Magnetic bearings Low loss Flywheel energy storage 2. Motors and generators Higher efficiency, lower loss, smaller machines 3. Medical device applications Drug delivery, MRI 4. Other applications 37

38 Flywheel Performance Applications of Bulk Superconductors 1. Magnetic bearings Low loss Flywheel energy storage 2. Motors and generators Higher efficiency, lower loss, smaller machines 3. Medical device applications Drug delivery, MRI 4. Other applications 38

Other applications DDS (Drug Delivery Systems) Targeted delivery of drugs in appropriate quantities Reduction of dosage

39 Applications of Bulk Superconductors 1. Magnetic bearings Low loss Flywheel energy storage 2. Motors and generators Higher efficiency, lower loss, smaller machines 3. Medical device applications Drug delivery, MRI 4. Other applications DDS (Drug Delivery Systems) Targeted delivery of drugs in appropriate quantities Reduction of dosage Reduction of side effects Enables: Treatment when surgery is difficult Effective treatment of obstinate diseases (Prof. S. Nishijima, Osaka University) 39

MRI 8 mm (c) (b) (a) (a) Photo of mouse embryo in 8 mm outer diameter

bulk superconducting magnet Applied Physics Letters (2011) 98 234101

Magnetic bearings Low loss Flywheel energy storage 2.

40 MRI 8 mm (c) (b) (a) (a) Photo of mouse embryo in 8 mm outer diameter sample tube 3D spin echo experiment (b) Sagittal Image of mouse embryo (c) Transversal Image of mouse embryo K. Ogawa et al, Development of a magnetic resonance microscope using a HTS bulk superconducting magnet Applied Physics Letters (2011) Applications of Bulk Superconductors 1. Magnetic bearings Low loss Flywheel energy storage 2. Motors and generators Higher efficiency, lower loss, smaller machines 3. Medical device applications Drug delivery, MRI 4. Other applications Madingley Lecture, 11th May

41 Seismic Stabilisation! Prof. Makoto TSUDA, Tohoku University LevMixer System Impeller levitated by a bulk superconductor rotates inside a sterile, single-use mixing system of up to 2000 litres for use in bio-process industry. 41

Conclusions and Summary There have been significant developments in the processing of bulk superconductor at Cambridge over the past 10 years; Flux pinning in bulk YBCO has been improved by

42 Conclusions and Summary There have been significant developments in the processing of bulk superconductor at Cambridge over the past 10 years; Flux pinning in bulk YBCO has been improved by engineering effective nano-scale flux pinning sites within the bulk microstructure; Average bulk Jc and trapped has been observed to increase with the addition of nano-scale Y2Ba4CuMOx phase particles in large grain Y-Ba-Cu-O; Development of generic seed crystal enabled the fabrication of GdBCO large, single grains using TSMG and shown to trap record magnetic flux densities of 17.6 T at 26 K; Multi-seeding is being developed and has significant potential for the manufacture of materials of practical geometry; TSIG is an emerging, reliable process; Record trapped field samples fabricated by a relatively straight forward process Conclusions and Summary for your attention 42

World Record, High Magnetic Fields from Bulk Superconductors

World Record, High Magnetic Fields from Bulk Superconductors Dr Mark Ainslie Royal Academy of Engineering (UK) Research Fellow CCD6-2015: The 6th Cryogenic Cluster Day, 23 September 2015 Bulk Superconductivity