Combination of natural and artificial flux pinning centres in BaZrO3 –doped YBa2Cu3O7 Films

Idea of nano-engineered pinning centres

Nano-dotstarget YBCO +BZO

target

LASER

STO substrate

YBCO

Ag

BZO nanorods

AFM image of Ag nano-dots on STO substrate deposited at temperature of 450 oC in vacuum with 15 laser pulses.

Formation of BZO nanorods in YBCO matrix

V.S. Dang a, P. Mikheenko a, A. Sarkar a, J.S. Abell a, P. Paturic, H. Huhtinenc, and A. Crisan a,b,*

a School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT , United Kingdomb National Institute of Materials Physics, Bucharest 077125, Romania

cWihuri Physical Laboratory, Department of Physics and Astronomy, FI-20014, University of Turku, Finland

Improvement of Jc of BZO-doped YBCO and Ag decorated BZO-doped YBCO

Conclusions and Acknowledgements

The financial support of the European Commission through the Marie Curie Excellence Grant MEXT-CT-2006-041111 “NanoTechPinningHTS”, the ESF-NES Network, and the Romanian Ministry of Education and Research, is gratefully acknowledged.

Ag substrate decoration is quite effective in increasing Jc in BZO doped YBCO thick and thin filmsJc of BZO-doped YBCO film has a maximum for fields along the c axis for applied fields smaller than 2.5 TBZO nano-rods and nanoparticles of Y2O and CuO or CuO2 are found in TEM images of the films. EDX Mapping confirmed existence of Y2O, CuO or CuO2 phases

-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

104

105

106

2.0mBZO-doped YBCO 15Ag/2.0mBZO-doped YBCO

J c(A

/cm

2 )

H(T)

65K

77.3K

0 90 180 270 3600.0

0.4

0.8

1.2 15Ag/0.4m BZO-doped YBCO 0.6m BZO-doped YBCO

V = 1 V

H || ab H || ab

H || c

77.3 K

J c (M

A/c

m2 )

(degree)

3T

We have investigated the combination of natural pining centres generated during deposition process of YBCO films, such as

Y2O3 nano-particles, with artificial pinning centres generated by Ag nano-dots and by BZO nano-inclusions in the YBCO target.

0 90 180 270 360

105

106

107

V = 1 V

H || abH || ab

H || c

77.3 K

J c (A/c

m2 )

(degree)

0.10.20.511.522.5

3

3.5

4

4.55

5.56

0 90 180 270 3608.0x104

1.0x105

1.2x105

1.4x105

1.6x105

1.8x105

(15Ag/1mBZO-doped YBCO)x2 1.8m BZO-doped YBCO

J c(A/c

m2 )

(Degree)

77.3KH//c

H//ab H//ab

2T

Cross section TEM images of Ag decorated BZO-doped YBCO films

a) b)c)

d)

b) c) d) e) f) g)a) h)

EDX mapping of BZO-doped YBCO film

a) STEM image b) Sr c) Y d) Cu e) Ba f) O

a) Field dependence of Jc of Ag decorated and undecorated BZO-doped YBCO films at 77.3 K and 65 K, the decorated film shows higher Jc in applied field from 1 T

b) Angular dependence of Jc of Ag decorated and undecorated BZO-doped YBCO filmsIn applied field of 3 T and temperature of 77.3 K

c) Angular dependence of Jc of Ag decorated and undecorated BZO-doped YBCO filmsIn applied field of 2 T and temperature of 77.3 K, films show dominance of Jc along the c axis

d) Angular dependence of Jc of Ag decorated BZO-doped YBCO film in applied fields from 0.1 T to 6 T and temperature of 77.3 K

Cross section TEM images of Ag decorated BZO-doped YBCO film, bright field, along (001) Zone axis, a) an overview, b) and c) BZO nano-rods in the YBCO matrix or Bamboo structure of BZO, d) Y2O3 nano-particle in the YBCO matrixe) CuO or CuO2 observed in the YBCO matrix, f) stacking fault, g) Image of boundary of the STO substrate and the film areas, h) Co-existence of Y2O3 (circle) and Cu rich phase (rectangular) and/or BZO phase.

Element mapping in STEM mode of Ag decorated BZO-doped YBCO film at the boundary between film and substrate, a) STEM image, b) Zr map, c) Y map, d) Cu map, e) Ba map, f) O map

The existence of areas with high density of Y or Cu and low density of Ba are marked by circles