Progress in development of MOCVDbased coated conductors Venkat Selvamanickam, Y. Yao, Y. Liu, J. Liu, N. Khatri, E Galtsyan, E. G lt and dG G. Majkic M jki Department p of Mechanical Engineering g 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. 1

Applied Superconductivity Conference, Portland, OR, October 8 – 12, 2012

4X HTS conductor performance improvement targeted for high power wind generators • Improved approaches to engineer nanoscale defects in coated conductors p g 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 g nanoscale defects 4x improved wire manufacturing

High-power, Efficient High-power Wind Turbines

• 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

Critical current at 30 K, 2.5 T (A/12 mm) (device operating condition)

750

End of project ~3000

price at device operating p g condition ($ ($/kA-m)) Wire p

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 Ic at operating temperature and field to Ic at 77 K, K zero field) in Ic of coated conductors at 30 K K, 2 2.5 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 Ic of today’s coated conductor previously improved by 2x by Zr addition 10.0

B ⊥ ⊥ tape

Jc (B)) / Jc (77 K, 0 T)

Field & Temperature

1.0

0.1 0

2

4

6

8

Magnetic Field (T) 77 K, 7.5% 65 K, 0% 40 K, 7.5% 30 K, 0%

77 K, 0% 50 K, 7.5% 40 K, 0% 20 K, 7.5%

65 K, 7.5% 50 K, 0% 30 K, 7.5% 20 K, 0%

Lift factor of Zr-doped tape is Zr-doped higher by 0.65 2.24

Lift Factor of 77 K, zero field Ic Undoped

65 K, 3 T

0.29

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 temperatures, 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

BZO spacing in 7.5%Zr sample : 35 nm BZO spacing in 15%Zr sample : 17 nm

15%Zr

Degradation in 77 K performance at higher Zr doping levels 94.0 77 K, 0 T

350

Tc

300

• Zero-field critical current drops beyond 7.5% Zr addition.

Ic

93 0 93.0 92.0

250 200

91 0 91.0

150

Tc (K)

Crittical curren nt (A/12 mm m)

400

• Sharper drop in Tc beyond 10% Zr addition (3 K from 10% - 25%)

90.0

100 89.0

50 0 0%

5%

10%

15%

20%

Z content Zr t t (%)

88.0 25%

HTS process p ocess

Optimal BZO O content

PLD

5 mol.%

MOD

10 mol% SUST 24, 25010 (2011)

MOCVD

7.5 Zr%

Reference

SUST 22, 085013 (2009)

Physica C. 469, 2037 (2009)

• Based three different HTS deposition techniques, optimal BZO content f best for b performance f at 77 K, K 1 T is i less l than h 10 mol.% l% • How to employ high levels of BZO (>> 10%) to introduce high density of nanoscale defects and still achieve good performance?

Deterioration in superconductor p quality q y with increasing Zr content 25% BZO

15% BZO

7.5% BZO

0% BZO 0% BZO (002) (005) (200) RE2O3 (006)

MOCVD process improved to achieve much better REBCO film crystallinity at high Zr levels (006)

MgO (200)

RE2O3 (005) (200) (002)

LMO (200)

BZO (200)

(103)

Previous process: 15%Zr

Improved process : 15%Zr

Significant g improvement p in 77 K performance p of tapes with high levels of Zr addition by modified MOCVD process 0.8 Tc

92.5

ΔTc

91.5

0.4

91 90.5

0.2

90 89.5 5%

0 10% 15% 20% 25% 30%

ΔTc (K)

06 0.6

92

Tc (K)

500

Critical currrent (A/12 mm)

93

77 K, zero field

450 400 350 300 250 200 Standard Process

150 100

Modified Process

50 0 0%

Zr addition

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% Z dd d tapes Zr-added t with ith modified difi d MOCVD process 30 K, 3 T ,

1800

7.5% Zr

1600

15% Zr modified  process

1400 1200 1000 800

Critical current (A A/12 mm)

Criticaal current ((A/12 mm)

2000

3000

7.5% Zr

2500

15%Zr, modified process

2000 1500 1000 500

30 K, B ⊥ tape

0

‐100‐80 ‐60 ‐40 ‐20 0 20 40 60 80 100120 Angle  between magnetic field and tape  normal (°) 

0

1

2

3

4

5

6

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%

7

8

9

1.E+05

4 1200

(006)

35 3.5

1000

3 2

600

1.5

400

1

200

1.E+04

Intenssity

2.5

800

Jc (MA A/cm2)

Critical curre C ent (A/12 mm m)

High critical currents in thick films of 15%Zradded GdYBCO tapes

LMO (200)

1 µm 2 µm 3 µm 4 µm 5 µm

(200)

1.E+03

0.5

0

0 1

2

3

HTS film thickness (µm)

4

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 g change g in microstructure even up to 5 µm HTS film thickness in 15%Zr films 2 µm

1 µm

2µm

2µm 3 µm

2µm

4 µm

2µm

5 µm

2 2µm

Ultra-high g critical currents in 15%Zr-added thick film tapes in high magnetic fields at 4.2K 7 4 2K B||c 4.2K, B||c

5000

15%Zr, 3 µm 7.5%Zr, 1.1 µm

4000

0%Zr, 1.1 µm

3000 2.8X 2000 1000

Jc (B) / Jc (77 7 K, 0 T)

Crittical curren nt (A/cm)

6000

4.2K, B||c , ||

6

15%Zr, 3 µm

5

7.5%Zr, 1.1 µm

4 3 2 1 0

0 0

2

4

6

8

10

Magnetic Field (T)

12

14

0

2

4

6

8

10

12

14

Magnetic Field (T)

Measurements by J. Jaroszynski, D. Abraimov, X. Hu and D. Larbalestier, NHMFL

• Ic = 3385 A/ A/cm att 4 4.2 2K K, 5 T (B|| (B||c), ) 2 2.8 8 titimes hi higher h th than previous i b bestt • 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 pp to further improve p infield 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 g density y of BZO nanorods over entire film thickness without interruptions possible

100 nm

20 nm

• N No significant i ifi t iin-plane l d defects f t to t interrupt i t t BZO nanorods d along l c-axis. i • 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 Y. Chen, Ch 4MJ 4MJ-01, 01 Thu, Th O Oct 11 11, 4 4:30 30 - 6:30 6 30 PM PM; “I “Interaction i b between B BaZrO Z O3 and d RE2O3 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 2G HTS MOCVD Wire at Intermediate and Low Temperatures” 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, Kesgin 3LPS-03 3LPS 03, Wed, Wed Oct 10 10, 2:00 - 3:30 PM; “Effect Effect of Selectively Electrodeposited • I. 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