Fabrication of cube textured NiO seed layer for YBCO coated conductor

Article abstract of DOI:10.1016/j.physc.2004.01.109

The cube textured NiO was formed on pure Ni tape using a simple approach of oxidizing the surface of the Ni tape for 3-20 min in air at 1130-1200 °C. The thickness of the NiO layer was about 1-5 μm. X-ray diffraction (XRD) θ-2θ scan, ω-scan, φ-scan, and pole figure were employed to characterize the in-plane alignment and cube texture of NiO film, and they showed that the NiO film was cube textured. The integrated intensity ratio of NiO I(200)/{I(200)+I(111)} was more than 99%, and the in-plane and out of plane full width at half maximum (FWHM) of the NiO buffer layer were 6.8° and 6.6°, respectively. Yttria-stabilized zirconia (YSZ) as a barrier layer and CeO₂ as a cap one were deposited by pulsed laser deposition (PLD), and YBa₂Cu₃O_7-x (YBCO) layer was prepared on them by PLD as well. YBCO superconducting layer with critical temperature (T_c)>88 K and critical current density (J_c) >4×10⁵ A/cm² (77 K, 0 T) has been obtained successfully on Ni tape with a textured NiO seed layer.

Full text of DOI:10.1016/j.physc.2004.01.109

Physica C 412–414 (2004) 844–847
www.elsevier.com/locate/physc
Fabrication of cube textured NiO seed layer for YBCO
coated conductor
a,
J. Yang , D.Q. Shi , C. Park , K.J. Song , R.K. Ko , H.Z. Liu , H.W. Gu
b
b
b
b
a
a
*
a
Superconducting Materials Research Center, General Research Institute for Non-ferrous Metals, Beijing 100088, PR China
b
Applied Superconductivity Group, Korea Electrotechnology Research Institute, Changwon, Kyung-nam 641-600, South Korea
Received 29 October 2003; accepted 6 January 2004
Available online 7 May 2004
Abstract
The cube textured NiO was formed on pure Ni tape using a simple approach of oxidizing the surface of the Ni tape
for 3–20 min in air at 1130–1200 ꢀC. The thickness of the NiO layer was about 1–5 lm. X-ray diffraction (XRD) h–2h
scan, x-scan, u-scan, and pole figure were employed to characterize the in-plane alignment and cube texture of NiO
film, and they showed that the NiO film was cube textured. The integrated intensity ratio of NiO I(2 0 0)/
{
I(2 0 0) + I(1 1 1)} was more than 99%, and the in-plane and out of plane full width at half maximum (FWHM) of the
as a cap
NiO buffer layer were 6.8ꢀ and 6.6ꢀ, respectively. Yttria-stabilized zirconia (YSZ) as a barrier layer and CeO
one were deposited by pulsed laser deposition (PLD), and YBa Cu
2
2
3
O
7ꢀx (YBCO) layer was prepared on them by PLD
5
as well. YBCO superconducting layer with critical temperature ðT
c
Þ > 88 K and critical current density ðJ
c
Þ > 4 ꢁ 10
2
A/cm (77 K, 0 T) has been obtained successfully on Ni tape with a textured NiO seed layer.
ꢁ
2004 Elsevier B.V. All rights reserved.
PACS: 74.72.Bk; 85.25.Kx; 81.65.Mq; 68.55.Jk
Keywords: YBCO coated conductor; NiO surface oxidation epitaxy; Cube textured
1
. Introduction
HTS wire, and high current carrying coated
conductors longer than several meters have been
reported since 2002. The current issues in coated
conductor include identifying more economical
manufacturing process of the multi-layer films,
improving the uniformity and reproducibility, and
increasing the current carrying capability.
Cube textured (1 0 0) [0 0 1] metal tapes, manu-
factured by thermo-mechanical treatment, have
been proven to be suitable substrates for coated
conductor process [1,2] when intermediate buffer
layers are inserted between metal and YBCO su-
perconducting layer. Matsumoto et al. [3] reported
High temperature superconducting (HTS)
wires/tapes which carry large amount of current in
high magnetic field are required for practical
applications, such as power electric devices and
high field magnets. There have been great pro-
gresses in the development of long-length coated
conductor, otherwise called the second generation
*
Corresponding author. Tel.: +86-10-8224-1256; fax: +86-
0-6237-6971.
E-mail address: yangjian@mail.grinm.com.cn (J. Yang).
1
0
921-4534/$ - see front matter ꢁ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.physc.2004.01.109

J. Yang et al. / Physica C 412–414 (2004) 844–847
845
the potential of the surface oxidation epitaxy
SOE) process for formation of a cube textured
X-ray diffraction (XRD) h–2h scan, x-scan, u-
scan, and pole figure were employed to charac-
terize the in-plane and out of plane alignment. The
surface morphologies were examined by optical
and scanning electron microscope (SEM). Energy
dispersive spectrum analysis (EDS) in the SEM
was used to evaluate phase compositions.
Furthermore, YSZ as a barrier layer and CeO2
as a cap one were deposited on Ni substrates with
NiO seed layer by pulsed laser deposition (PLD),
and YBCO layer was prepared by PLD as well.
The thickness of YBCO was less than 380 nm. The
electrical properties of the YBCO film were mea-
sured by standard four-probe method with a cri-
terion of 1 lV/cm for full width of sample.
(
NiO buffer on the textured Ni. This NiO can be
epitaxially grown by direct oxidation of the tape
surface. Results of the SOE process for coated
conductors have been reported by many research
groups [4–8]. In our work, Ni tapes were treated
under the different oxidation conditions to form
cube textured NiO which can be used as the first
layer of the buffer architecture. The aims were to
prevent the interaction between the YBCO and the
metal substrate, and to hinder unexpected forma-
tion of the NiO(1 1 1) during deposition of buffer
and superconducting layers for YBCO coated
conductor by the SOE process. SOE process was
found to be a simple and low cost technique which
is suitable for long-length tape. Biaxially textured
NiO seed layer was formed by controlling the
oxidation conditions, as well as the texture of Ni
substrate. In order to smoothen or flatten the
surface roughness and to reduce mismatch with
3. Results and discussion
The highly cube textured Ni tapes were ob-
tained by cold rolling process followed by recrys-
tallization thermal treatment. On the textured Ni
tapes, cube textured NiO was formed using SOE
technique in air at the oxidation temperature of
1110–1250 ꢀC for 3–30 min. The thickness of the
NiO layer was about 1–5 lm. It has been found
that the texture of NiO layer in SOE process was
affected enormously by oxidation temperature and
time, as well as the texture and morphology of the
Ni substrate. When oxidation was carried out at
the temperature in the ranging from 1130–1200 ꢀC
for 3–30 min, NiO film was formed on Ni tape
with a cube texture. The integrated intensity ratio
of NiO I(2 0 0)/{I(2 0 0) + I(1 1 1)} was more than
99% under above mentioned oxidation condition.
When the temperature was lower than 1100 ꢀC, the
(1 1 1) peak of NiO appeared. When the tempera-
ture was higher than 1250 ꢀC and the oxidation
time was longer, the surface of NiO would become
rougher. That was because the grain size
increased in higher temperature than 1250 ꢀC.
Furthermore, the rate of heating and cooling
temperature was an important factor for cube
texture of NiO. In our work, the samples were
directly placed a hot air furnace, in order to pre-
vent the formation of a pre-existing NiO(1 1 1) film
during placing samples into the furnace through
lower temperature.
2
YBCO, YSZ and CeO films were deposited on Ni
substrate with NiO seed layer before YBCO
deposition. The J at liquid nitrogen temperature
c
5
2
was more than 4 · 10 A/cm .
2
. Experimental
Pure Ni was introduced into the (1 0 0) [0 0 1]
cube texture by cold rolling with deformation in
excess of 98% to the final thickness of 0.1–0.15 mm,
followed by recrystallization thermal treatment for
1
(
7
h at 900–1000 ꢀC. The Ni tapes have a typical
1 0 0) [0 0 1] cube texture with in-plane FWHM of
–9ꢀ. Prior to oxidation, Ni tapes were cut into
small pieces. Chemical polishing was performed to
Ni samples before SOE process, and then the Ni
samples were ultrasonically cleaned in acetone.
The surface oxidation process was conducted in
a horizontal tube furnace. The NiO growth in air
was carried out at temperature range of 1100–1250
ꢀ
C. When the furnace was heated to the required
temperature, the sample was put into the furnace
directly. After pre-determined oxidation time at
high temperature, the sample was rapidly taken
out of the furnace and cooled down to the room
temperature in air.

846
J. Yang et al. / Physica C 412–414 (2004) 844–847
The X-ray u-scans of Ni(1 1 1) and NiO(1 1 1)
peaks are shown in Fig. 1, which demonstrates
that the (1 0 0) textured NiO was obtained on the
Ni surface with cube-on-cube orientation. High in-
plane alignment of the NiO buffer layer can be
seen from u-scan. The average FWHM from X-
ray u-scan values for Ni(1 1 1) and NiO(1 1 1) are
6
.8ꢀ and 6.6ꢀ, respectively. Fig. 2 presents the X-
ray rocking curve of NiO(2 0 0) peak. The FWHM
of 6.3ꢀ is similar to that of the Ni substrate. Fig. 3
shows the pole figure of NiO(1 1 1), which implies
an excellent cube texture.
Fig. 3. X-ray pole figure of NiO(1 1 1): (a) NiO(1 1 1) 2D pole
figure. (b) NiO(1 1 1) 2.5D pole figure.
The SEM was used to study the surface mor-
phology of NiO films, and typical result is shown
in Fig. 4. No crack was found, but defects such as
droplets, pin holes were observed. Some out-
growths of NiO occurred around Ni grain
boundaries which were not beneficial to the
deposition of YBCO on it.
In order to improve the surface morphology of
a buffer layer and enhance lattice match between
Ni(111)
NiO(111)
0
100
200
ϕ(deg.)
300
400
0
100
200
300
400
Fig. 4. SEM surface morphology of NiO grown on Ni tape by
SOE process.
ϕ(deg.)
(
a)
(b)
Fig. 1. X-ray u-scan for (a) NiO(1 1 1) by SOE process and (b)
Ni(1 1 1) substrate by rolling and annealing process.
2
buffer layer and YBCO layer, YSZ and CeO films
were inserted as barrier and cap layers. And then
YBCO was grown by pulsed laser deposition on a
2
YSZ/CeO /NiO buffered Ni substrate. The best
YBCO film fabricated on such buffered Ni showed
a T onset of 91.5 K and a zero resistance at 88.4
NiO(200)
c
K. The resistance versus temperature data is
shown in the insert of Fig. 5. Fig. 5 describes that
the I
c
value in self-field and at 77 K is 14 A for 7.5
values
mm width sample. For most samples, J
c
5
2
were in the range of 4–5 · 10 A/cm (0 T, 77 K).
The rough surface of the NiO layer, which can lead
to rough surface and lower degree of texture of the
layers deposited on the NiO, is believed to limit the
critical current.
5
10 15 20 25 30 35 40
θ(deg.)
Fig. 2. X-ray x-scan for (2 0 0) peak of NiO grown on Ni tape
by SOE process.

J. Yang et al. / Physica C 412–414 (2004) 844–847
847
successfully on Ni tapes with a textured NiO seed
layer.
1
1
20
00
Tc=88.4K
8
0
0
0
0
Acknowledgements
6
4
2
76
80 84 88 92 96 100
Temp(K)
This work was supported by 863 program of the
Ministry of Science and Technology of China.
0
(program number: 2002AA306211)
-
2 0 2 4 6 8 10121416182022
Current(A)
References
Fig. 5. Critical current of the YBCO film deposited on the
CeO /YSZ/NiO buffered Ni. Inset shows resistance versus
temperature data for YBCO.
2
[1] A. Goyal, D.P. Norton, J. Budai, M. Parantharam, E.D.
Specht, D.M. Kroeger, D.K. Christen, Q. He, B. Sa.an, F.A.
List, D.F. Lee, P.M. Martin, C.E. Klubunde, E. Hat.eld,
V.K Sikka, Appl. Phys. Lett. 69 (1996) 1795.
4
. Summary
[
2] D.P. Norton, A. Goyal, J.D. Budai, D.K. Christen, D.M.
Kroeger, E.D. Specht, Q. He, B. Saffian, M. Paranthaman,
C.E. Klabunde, D.F. Lee, B.C. Sales, F.A. List, Science 274
The highly cube textured NiO seed layer on
textured pure Ni tape was successfully obtained by
SOE technique. The integrated intensity ratio of
NiO I(2 0 0)/{I(2 0 0) + I(1 1 1)} was more than
(
1996) 755.
[3] K. Matsumoto, S.B. Kim, J.G. Wen, I. Hirabayashi, T.
Watanabe, N. Uno, M. Ikeda, IEEE Trans. Appl. Supercon.
9
(1999) 1539.
9
9%, and the in-plane and out of plane FWHM of
[
[
4] K. Matsumoto, A. Takechi, T. Ono, I. Hirabayashi, K.
Osamura, IEEE Trans. Appl. Supercon. 13 (2003) 2535.
5] D.Q. Shi, M. Ionescu, J. McKinnon, W.M. Chen, S.X. Dou,
Cryog. Eng. 48 (2002) 525.
the NiO seed layer were 6.8ꢀ and 6.6ꢀ, respectively.
The SEM observation implied that the surface
morphology of NiO film was crack-free, even
though it was not very smooth. YSZ as a barrier
[6] M. Kai, T. Izumi, K. Hasegawa, Y. Tokunaga, S. Asada, Y.
Nakamura, T. Izumi, T. Watanabe, Y. Shiohara, Physica C
2
layer and CeO as a cap one were deposited by
3
78–381 (2002) 998.
PLD, and YBCO layer was prepared by PLD as
well. As a consequence of investigation, YBCO
superconducting coatings with a high c-axis ori-
entation, high T exceeding 88 K and J higher
[
7] Z. Lockman, X. Qi, A. Berenov, W. Goldacker, R. Nast, B.
deBoer, B. Holzapfel, J.L. MacManus-Driscoll, Physica C
383 (2002) 127.
[8] T. Watanabe, Y. Ohashi, T. Maeda, M. Mimura, I.
Hirabayashi, IEEE Trans. Appl. Supercon. 13 (2003) 2484.
c
c
5
2
than 4 · 10 A/cm at 77 K, 0 T have been obtained