Progress in development of MOCVDbased coated conductors Venkat Selvamanickam, Y. Yao, Y. Liu, J. Liu, N. Khatri, E. Galtsyan, and dg. Majkic Department of Mechanical Engineering g Texas Center for Superconductivity University of Houston, Houston, TX, USA Y. Chen and C. Lei SuperPower Inc., Schenectady, NY, USA Funded by Advanced Research Projects Agency-Energy (ARPA-E) award DE-AR0000196. Applied Superconductivity Conference, Portland, OR, October 8 12, 2012 1
4X HTS conductor performance improvement targeted for high power wind generators Improved approaches to engineer nanoscale defects in coated conductors in ARPA-E funded program. New pilot MOCVD system set up in UH Energy Research Park to rapidly scale up new technology advances to long-length manufacturing. Engineered nanoscale defects High-power, Efficient Wind Turbines 4x improved wire manufacturing Quadrupling superconductor Performance at 30 K, 2.5 T for commercialization of 10 MW wind generators to reduce wire cost by 4x Advances will also lead to high-performance HTS conductors for other high-field applications
4X HTS conductor can enable commercial feasibility of HTS devices Metric Now End of project Critical current at 30 K, 2.5 T (A/12 mm) (device operating condition) 750 ~3000 Wire price at device operating condition ($/ka-m) 144 36 Estimated HTS wire required for a 10 MW generator (m) 65,000 16,250 Estimated HTS wire cost for a 10 MW generator $ (,000) 7,020 1,755 Quadruple the critical current performance to 3,000 A at 30 K and 2.5 T Doubling the lift factor (ratio of I c at operating temperature and field to I c at 77 K, zero field) in I c of coated conductors at 30 K, 2.5 T by engineering nanoscale defect structures in the superconducting film. Additional near doubling of critical current by thicker superconducting films while maintaining the efficacy of pinning by nanostructures. 3
In-field I c of today s coated conductor previously improved by 2x by Zr addition 0 T) J c (B) / J c (77 K, 10.0 1.0 0.1 B tape 0 2 4 6 8 Magnetic Field (T) 77 K, 7.5% 77 K, 0% 65 K, 7.5% 65 K, 0% 50 K, 7.5% 50 K, 0% 40 K, 7.5% 40 K, 0% 30 K, 7.5% 30 K, 0% 20 K, 7.5% 20 K, 0% Lift Factor of Lift factor of Field & 77 K, zero field I c Zr-doped Temperature tape is Undoped Zr-doped higher by 65 K, 3 T 0.29 0.65 2.24 50 K, 3 T 0.65 1.4 2.15 40 K, 3 T 0.91 2.0 2.2 30 K, 3 T 1.38 2.72 1.97 20 K, 3 T 1.80 3.45 1.92 At 3 T, over a wide range of temperatures, quantity of HTS conductor required for device is reduced by ½ which greatly improves the economics of the device. Goal is to achieve another 2x improvement in lift factor at 30 K, 2.5T
Opportunities to further improve pinning with higher density of BZO defects in high Zr content tapes 7.5%Zr 15%Zr BZO spacing in 7.5%Zr sample : 35 nm BZO spacing in 15%Zr sample : 17 nm
Crit tical curren nt (A/12 mm m) Degradation in 77 K performance at higher Zr doping levels 400 350 300 250 200 150 100 50 77 K, 0 T Ic Tc 94.0 93.0 92.0 91.0 90.0 89.0 0 88.0 0% 5% 10% 15% 20% 25% Zr content t (%) (K) T c Zero-field critical current drops beyond 7.5% Zr addition. Sharper drop in T c beyond 10% Zr addition (3 K from 10% - 25%) HTS process Optimal BZO content Reference PLD 5 mol.% SUST 22, 085013 (2009) MOD 10 mol% SUST 24, 25010 (2011) MOCVD 7.5 Zr% Physica C. 469, 2037 (2009) Based three different HTS deposition techniques, optimal BZO content for best performance at 77 K, 1 T is less than 10 mol.% How to employ high levels of BZO (>> 10%) to introduce high density of nanoscale defects and still achieve good performance?
Deterioration in superconductor quality with increasing Zr content 25% BZO 15% BZO 7.5% BZO 0% BZO (006) (005) (200) RE 2 O 3 (002)
MOCVD process improved to achieve much better REBCO film crystallinity at high Zr levels (006) MgO (200) (005) RE 2 O 3 (200) (002) LMO (200) BZO (200) (103) Previous process: 15%Zr Improved process : 15%Zr
Significant improvement in 77 K performance of tapes with high levels of Zr addition by modified MOCVD process T c (K) 93 92.5 92 91.5 91 90.5 90 0.8 Tc ΔTc 06 0.6 89.5 0 5% 10% 15% 20% 25% 30% Zr addition 0.4 0.2 ΔT c (K) mm) Critical cur rrent (A/12 500 450 400 350 300 250 200 150 100 50 0 Standard Process Modified Process 77 K, zero field 0% 5% 10% 15% 20% 25% 30% Zr content Opportunity to now to benefit from high defect density with high levels of Zr addition 9
Significant improvement in performance of 15% Zr-added d tapes with modified d MOCVD process Critica al current (A/12 mm) 2000 1800 1600 1400 1200 1000 800 7.5% Zr 15% Zr modified process 100 80 60 40 20 0 20 40 60 80 100120 Angle between magnetic field and tape normal ( ) 30 K, 3 T 3000 7.5% Zr current (A A/12 mm) Critical 2500 2000 1500 1000 500 0 30 K, B tape 15%Zr, modified process 0 1 2 3 4 5 6 7 8 9 Magnetic field (T) Critical current of 15% Zr-added film ~ 1100 A/12 mm at 30 K, 3 T, B c Lift factor at 30K, 3 T, B c improved by 40-65%
High critical currents in thick films of 15%Zradded GdYBCO tapes Critical curre ent (A/12 mm m) 1200 1000 800 600 400 200 4 35 3.5 3 2.5 2 1.5 1 0.5 Jc (MA A/cm 2 ) Intens 1.E+05 sity 1.E+04 1.E+03 LMO (200) (006) (200) 1 µm 2 µm 3 µm 4 µm 5 µm 0 1 2 3 4 HTS film thickness (µm) 0 1.E+02 45 46 47 48 2theta ( ) Combining thick film and improved pinning compositions to achieve high critical currents in high magnetic fields. No significant a-axis oriented growth found even in 5 µm thick films 11
No significant change in microstructure even up to 5 µm HTS film thickness in 15%Zr films 1 µm 2 µm 2µm 2µm 3 µm 4 µm 5 µm 2µm 2µm 2µm
Crit tical curren nt (A/cm) Ultra-high critical currents in 15%Zr-added thick film tapes in high magnetic fields at 4.2K 6000 5000 4000 3000 2000 1000 0 2.8X 42K 4.2K, B c 15%Zr, 3 µm 7.5%Zr, 1.1 µm 0%Zr, 1.1 µm 0 2 4 6 8 10 12 14 Magnetic Field (T) c (B) / J c (77 7 K, 0 T) J c 7 6 5 4 3 2 1 0 4.2K, B c 15%Zr, 3 µm 7.5%Zr, 1.1 µm 0 2 4 6 8 10 12 14 Magnetic Field (T) Measurements by J. Jaroszynski, D. Abraimov, X. Hu and D. Larbalestier, NHMFL I c = 3385 A/cm at 4.2 K, 5 T (B c), 2.8 times higher h than previous best Improvement from pinning (lift factor) is 25% higher in 15%Zr-tape at 4.2 K, 5 T (B c) than previous-best 7.5%Zr-added tape 13
Several opportunities to further improve in- field performance Increase density of nanoscale defects Introduce nanoscale defects that are even more effective at low temperatures and high fields Modify growth process for longer nanorods without interruptions 5 nm Average size 3.9nm Average distance ~12nm 14
Interruptions to vertical nanorods by defects along the a-b plane: Opportunity to improve 100 nm 20 nm
High density of BZO nanorods over entire film thickness without interruptions possible 100 nm 20 nm No significant ifi in-plane defects to interrupt t BZO nanorods along c-axis. 77 K, zero-field critical current needs to be improved
Upcoming papers of the Houston Group at ASC Improved pinning and critical currents in coated conductors Y. Liu, 4MJ-05, Thu, Oct 11, 4:30-6:30 PM; Electromagnetic properties of high-zr content GdYBCO tapes Y. Chen, 4MJ-01, Thu, Oct 11, 4:30-6:30 PM; Interaction between BaZrO 3 and RE 2 O 3 pinning centers in Zr:GdYBCO HTS tapes G. Majkic, 3MPE-05, Wed, Oct 10, 9:00-10:30 AM; Effect of High BZO Dopant Levels on Performance of 2G-HTS MOCVD Wire at Intermediate and Low Temperatures C. Lei, 2ME-05, Tue, Oct 9, 3:30-5:30 PM; The structural evolution of (Gd,Y)BaCuO tapes with Zr addition made by metal organic chemical vapor deposition N. D. Khatri, 2MA-02, Tue, Oct 9, 10:30 AM - 12:30 PM; Pre-fabricated Metal Nanorods on Biaxially-textured Substrates for REBCO Pinning Superconductors Low ac loss coated conductors I. Kesgin, 3LPS-03 03, Wed, Oct 10, 2:00-3:30 PM; Effect of Selectively Electrodeposited Stabilizer Thickness on AC Loss Behavior of Fully-Filamentized 2G-HTS Wire X. Cai, 3MPE-01, Wed, Oct 10, 9:00-10:30 AM; Completely Etch-free Fabrication of Multifilamentary 2G-HTS Tapes Using Inkjet Printing and Electrodeposition Delamination in coated conductors E. Galstyan, 4MPC-01, Thu, Oct 11, 9:00-10:30 AM. Investigation of Delamination Mechanisms in REBCO Coated Conductors 17