The J c Dependence on Oxygen Doping in Polycrystalline Forms of - PowerPoint PPT Presentation

The J c Dependence on Oxygen Doping in Polycrystalline Forms of Bi-2212 with Various Textures M O Rikel a , A Hobl a , J Ehrenberg a , J Bock a , S Elschner b , A Dellicour c, d, e , D Chateigner c , B Vertruyen d , J-F Fagnard d , P.Vanderbemden d a Nexans SuperConductors GmbH, Hürth, Germany b University of Applied Science, Mannheim, Germany c CRISMAT-ENSICAEN, University of Caen Basse-Normandie, France d SUPRATECS, University of Liege, Belgium e Internatinal Doctoral School on Functional Materials 1/21 Sept 2002 / 1 Nexans ¡SuperC onductors 2MC-06 ASC’2012, Portland, October 9, 2012

Acknowledgments l D C Larbalestier, F Kametani, J Jiang, A Polyanskii, E. Hellstrom (NHMFL, Tallahassee) l H Miao, Y Huang, J Parrell, S Hong (OST, Carteret) l C. Scheuerlein, A Ballarino, L Bottura (CERN, Geneva). l S Krämer, J Schramm, C Janke, C Migge, R Deul, Z Abdoulaeva, W Horst, A Klimt, S Hardenberg, J Schütz, D Kobersky, M Gross (NSC, Hürth) l M Matras, V Moreau, (ENSCI, Limoges); E. Lugand (EPF, Paris) l L Lutterotti (University of Trento ) 2/21 Sept 2002 / 2 2MC-06 ASC’2012, Portland, October 9, 2012

Melt Cast Processed Bi2212 Bulk Je(77 K; sf) ~ 1 kA/cm 2 12 KV/100 & 800 A FCLs > 1 T Magnetic Screen @ 10 K J-F Fagnard et al, Supercond. Sci. Technol. 23 (2010) 095012 (8 pp) 3/21 Sept 2002 / 3 2MC-06 ASC’2012, Portland, October 9, 2012

Optimization of Jc(T) in Bi2212 MCP Bulk How SuperCurrent flows? What limits current ? 4/21 Sept 2002 / 4 2MC-06 ASC’2012, Portland, October 9, 2012

Bicrystal Jc vs Misorientation Angle Data for 2212 H. Hilgenkamp and J. Mannhart, Rev. Mod. Phys., Vol. 74, No. 2, 2002, pp. 485-549. 5/21 Sept 2002 / 5 2MC-06 ASC’2012, Portland, October 9, 2012

2212 Round Wires and Bulk: High Jc in the absence of Long-Range Texture Melt Cast Processed 2212 Despite absence of long-range texture powder-in-tube (PIT) Bi-2212 round wire can carry remarkably high J c values (~10 5 A/cm 2 at 45 T and Almost no Local Texture 4.2 K) Shen et al, Applied Physics Letters J c (77 K, 0 T) ~ 5 kA/cm 2 95 , 152516 (2009)]. J c (66 K = 0.7 T c ) ~ 15 kA/cm 2 ~ 20% of best J c (77 K = 0.7 T c ) in Ag/Bi2223 6/21 Sept 2002 / 6 2MC-06 ASC’2012, Portland, October 9, 2012

What is Unique in Bi2212 that SuperCurrent Flows across High-Angle GBs ? l Role of O overdoping Shen et al (2009); Rikel et al (2011) Bulk of the grain Bulk of the grain GB GB l Special Nature of High-Angle GBs Kametani et al 2008, 2010 (2MC-07) 7/21 Sept 2002 / 7 2MC-06 ASC’2012, Portland, October 9, 2012

Role of O Overdoping The J c (77K, sf) dependence on O contents in Bi 2 Sr 2 CaCu 2 O 8+ δ l MCP bulk rods and tubes with only slight preferred orientation l textured Ag sheathed round wires (19x85; 1.2 mm ∅ ; OST), l textured Ag sheathed tapes Difference in texture => Difference in the dominant type of GBs => Difference in the optimum overdoping 8/21 Sept 2002 / 8 2MC-06 ASC’2012, Portland, October 9, 2012

Jc(77 K, sf) vs Oxygen Contents. Optimum overdoping 100 2000 95 1600 <J e (77 K, sf)>, A/cm 2 90 1200 T c , K 85 800 Tc Data of Optimum δ Schweizer et al 1993 0.202 for tube Tc of MCP-Bulk (21-T-36h ) 80 400 Jc in 49.2/43 mm dia tube 0.204 for 8 mm rod Jc 8 mm dia rods 0.212 for OST RW Jc 1.2 mm dia RW 75 0 0.16 0.17 0.18 0.19 0.20 0.21 0.22 0.23 0.24 δ in Bi 2 Sr 2 CaCu 2 O 8+ δ Rikel et al 2011 (EUCAS) 9/21 Sept 2002 / 9 2MC-06 ASC’2012, Portland, October 9, 2012

Variation of Oxygen Contents The δ - p O 2 - T diagram of Approach of Glowacki et al (2003) , Schweizer et al (1993) Yamashita et al (2010) 0 Delta =0.180 Delta = 0.192 log(pO2 [atm]) -1 Delta = 0.198 Delta = 0.205 -2 -3 -4 -5 3 4 5 6 7 8 9 x = T/100, °C l Anneal at high T for fast equilibration; l Cool down along the p O 2 - T cooling trajectory to suppress O exchange l Proof of consistency : Changes in δ measured for bulk using gravimetry give a good agreement with anticipations 10/21 Sept 2002 / 10 2MC-06 ASC’2012, Portland, October 9, 2012

Texture in Bi2212. Multifilamentary Wires F Kametani et al SuST 2011 <FWHM> ~ 15° C Scheuerlein et al 2011 11/21 Sept 2002 / 11 2MC-06 ASC’2012, Portland, October 9, 2012

Texture in bulk Bi2212. Approach B i 2 2 1 2 b u l k 1 3 4 - 8 ( 5 ) x = 2 ,0 c h i = 0 ( K a 1 , 8 .6 K ) B i 2 2 1 2 p o w d e r # 4 3 1 1 4 7 3 2 0 1 ( K a 1 2 . 5 K ) 2 0 0 2 0 0 1 0 0 B i2 2 1 2 P O = 1 . 7 9 2 8 0 6 0 I n t , % 1 1 5 4 0 1 1 3 1 1 7 2 0 2 0 2 2 0 0 , 1 1 1 1 0 0 1 2 0 0 1 0 0 0 1 1 0 0 1 3 0 0 8 0 1 7 1 1 9 1 0 8 0 0 9 0 2 5 3 0 3 5 Normalized March-Dolase Function 2 θ , d e g s 5 180 ( A / A ) ( A / A ) P ( ) 4 PO=2.25 = × ϕ P ( ϕ d ) / 180 1 ∫ ϕ = hkl 200 hkl 200 RP hkl 0 3 ⎠ ) 2 2 1 2 3 / 2 P( ⎠ P ( ) ( PO cos PO sin ) − − ϕ = ϕ + ϕ FWHM 2 1 ϕ hkl = ϕ = an angle between hkl and 001 0 0 20 40 60 80 100 120 140 160 180 ϕ , ° 12/21 Sept 2002 / 12 2MC-06 ASC’2012, Portland, October 9, 2012

Texture in bulk Bi2212. Rough Estimates 1.8 Tube 136-12 ( ∅ out: 50/in: 35 mm) Sample #1 Sample #2 1.6 1.4 PO 00 L PO 1.2 PO =1 => isotropic 2212 at outer & inner 1.0 surfaces 0.8 FWHM ~ 50° 0.6 0 1 2 3 4 5 6 7 8 Depth, mm Distance from the surface, mm R 8 mm rods R45, 3905 2 2 PO 2 r PO ( r ) dr /( R r ) < >= ∫ − r Sample < PO > < FWH M> , ¡° 49/43 ¡mm ¡ 1.40(6) 60(5) 8 ¡mm ¡rod 1.71(4) 44(3) FWHM ~ 15-20° 5 ¡mm ¡rod 1.91(8) 37(3) 13/21 Sept 2002 / 13 2MC-06 ASC’2012, Portland, October 9, 2012

Samples Studied . Texture Summary l Bi2212 Bulk (Nexans) l Fiber Texture <FWHM> ~ 60° ◗ MCP Tubes ◗ OD/ID = 49/43 mm MCP rods ◗ <FWHM> ~45-35° 8 and 5 mm diameter ◗ n l OST Bi2212 Round Wires l AzimuthalTexture melt processed at OST for optimizing <FWHM> ~ 15° Je(4.2K, 12 T) = 400 A/mm 2 ◗ in 1 m long barrel samples Optimum δ 0.202 for tube 0.204 for 8 mm rod 0.212 for OST RW 14/21 Sept 2002 / 14 2MC-06 ASC’2012, Portland, October 9, 2012

Samples Summary. Caton Composition l Cation composition l Bi2212 Bulk (Nexans) Sr/Ca = 2.35(8) ◗ MCP Tubes OD/ID = 49/43 mm ◗ to reach Tc ~ 94.5 K MCP rods 8 and 5 mm diameter ◗ l Bi 2.15 Sr 1.95 Ca 0.90 Cu 2.00 O 8+ δ l OST Bi2212 Round Wires melt processed at OST for optimizing Sr/Ca = 2.18(3 ) ◗ Je(4.2K, 12 T) = 400 A/mm 2 in 1 m long barrel samples l Bi 2.15 Sr 1.95 Ca 0.90 Cu 2.00 O 8+ δ l MCP rods 8 mm diameter (precursor lot 79) Sr/Ca = 2.18(3 ) ◗ 15/21 Sept 2002 / 15 2MC-06 ASC’2012, Portland, October 9, 2012

Jc vs δ in Bi 2 Sr 2 CaCu 2 O 8+ δ

Refined Jc( δ ) for Bulk Δδ 0 = 0.013 (8) δ 0 = 0.203(2) <FWHM>, ° 60 44 37 δ 0 = 0.190(8) δ in Bi 2 Sr 2 CaCu 2 O 8+ δ 17/21 Sept 2002 / 17 2MC-06 ASC’2012, Portland, October 9, 2012

Tc & Ic vs δ in OST RW Δδ 0 = 0.018(8) vs 0.013 (8) in bulk δ 0 = 0.195(7) δ 0 = 0.213(4) δ in Bi 2 Sr 2 CaCu 2 O 8+ δ 18/21 Sept 2002 / 18 2MC-06 ASC’2012, Portland, October 9, 2012

Ic in Rods and Wire. The same Composition Bi 2.15 Sr 1.95 Ca 0.90 Cu 2.00 O 8+ δ δ 0 = 0.215(3) δ 0 = 0.213(4) δ in Bi 2 Sr 2 CaCu 2 O 8+ δ 19/21 Sept 2002 / 19 2MC-06 ASC’2012, Portland, October 9, 2012

Conclusion l Overdoping Bi2212 is necessary to optimize Ic lower application temperatures need larger overdoping l The level of overdoping for maximum Jc is within the error independent of the material texture (FWHM from 15 to 60°) Δδ 0 = 0.018(8) in RW vs 0.013(8) in Bi2212 bulk δ 0 = 0.213(4) in RW vs 0.215(5) in Bi2212 bulk l The O contents optimum for Ic is strongly dependent on cation composition: δ 0 = 0.203(2) for Sr/Ca = 2.35(8) δ 0 = 0.214(3) for Sr/Ca = 2.18(3) 20/21 Sept 2002 / 20 2MC-06 ASC’2012, Portland, October 9, 2012

Practical Consequences l Optimizing O doping, we improved performance of Bi2212 bulk at 77 K by 20 to 50% Ic(77K,sf) ~ 600 A in 8 mm rods; 6.3 kA in 49/43 mm (OD/ID) tubes l Optimization of Bi2212 bulk for applications at lower T should include optimization of cation composition and O doping Magnetic screens / Trapped-field magnets for 3-5 T at 10-20 K could be possible l Optimizing O doping should be a part of compositional studies for OPIT round wires: 21/21 Sept 2002 / 21 2MC-06 ASC’2012, Portland, October 9, 2012

Thank you for your attention

Overdoping at 66 K δ 0 = 0.218(3) δ 0 = 0.213(4) δ in Bi 2 Sr 2 CaCu 2 O 8+ δ in agreement with data of Matsumoto et al (2004) on Bi2212 OPIT wire 23/21 Sept 2002 / 23 2MC-06 ASC’2012, Portland, October 9, 2012

OST-Nexans Data 2004-2006 2000 W521 (b) W522 1600 W523 2 1200 J e , A/mm W524 800 400 0 882 884 886 888 890 892 894 896 898 900 T max , °C Why overall composition of Bi2212 has such a strong effect on performance of round wires and tapes ? 24/21 Sept 2002 / 24 2MC-06 ASC’2012, Portland, October 9, 2012