scholarly journals High Temperature Superconducting Thick Films by use of EPD Method (II)

2017 ◽  
Vol 5 (1) ◽  
pp. 69
Author(s):  
Soh Deawha ◽  
N. Korobova ◽  
Park Jungcheul
Keyword(s):  
High Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Thick Films ◽  
Film Surface ◽  
Deposition Method ◽  
Ybco Films ◽  
High Temperature Superconducting ◽  
Superconducting Thick Films

<p>High temperature superconducting (HTS) thick films deposited on metal Ag wire were prepared with YBCO and BSCCO powders by electrophoretic deposition method. I<sub>2</sub> was used as additives for surface charge of YBCO and BSCCO particles. When 2-3 wt.% BaF<sub>2</sub> was added in the YBCO suspension, the pores and cracks of film surface were decreased and film density could be increased. In case of YBCO films, the critical current density (J<sub>c</sub>) was calculated at the value of 1458 A/cm<sup>2</sup> (77 K, 0 K) by 4 point prove method. BSCCO films had less cracks than YBCO films, and the critical current density (J<sub>c</sub>) was obtained more than 10<sup>4</sup> A/cm<sup>2</sup>.</p>

Thickness dependence of microstructure and critical current density of Yba2Cu3O7−δ on rolling-assisted biaxially textured substrates

2003 ◽  
Vol 18 (5) ◽  
pp. 1109-1122 ◽  
Author(s):  
K. J. Leonard ◽  
A. Goyal ◽  
D. M. Kroeger ◽  
J. W. Jones ◽  
S. Kang ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Ybco Film ◽  
Cube Texture ◽  
Film Surface ◽  
Second Phase ◽  
Film Properties ◽  
Cross Sectional ◽  
Ybco Films

The change in microstructure associated with the decrease in critical current density (Jc) of Yba2Cu3O7−δ (YBCO) films with increasing thickness was examined. Samples of pulse laser deposited YBCO films varying in thickness from 0.19 to 3.0 μm on rolling-assisted biaxially textured substrates with an architecture of CeO2/YSZ/CeO2/Ni were prepared by tripod polishing for cross-sectional electron microscopy. More randomly oriented grains in the upper portion of the YBCO film surface were observed with increasing film thickness, resulting in less cube texture. In addition, increases in mismatch across the boundaries of the c-axis grains with increasing time during deposition, along with the development of BaCeO3 and Y2BaCuO5 phases at the YBCO/CeO2 interface, contributed to the degradation of film properties. Surface outgrowths of the YBCO film were examined as well as the defect structures and second-phase formations within the films.

Evidence for Extensive Grain Boundary Meander and Overgrowth of Substrate Grain Boundaries in High Critical Current Density ex Situ YBa2Cu3O7−x Coated Conductors

2005 ◽  
Vol 20 (8) ◽  
pp. 2012-2020 ◽  
Author(s):  
D.M. Feldmann ◽  
D.C. Larbalestier ◽  
T. Holesinger ◽  
R. Feenstra ◽  
A.A. Gapud ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Film Thickness ◽  
Critical Current ◽  
Current Density ◽  
Thick Films ◽  
Coated Conductors ◽  
Ex Situ ◽  
High Critical Current Density ◽  
Ybco Films

It has been generally accepted that YBa2Cu3O7−x (YBCO) films deposited on deformation textured polycrystalline metal tapes result in YBCO grain boundary (GB) networks that essentially replicate the GBs of the underlying substrate. Here we report that for thicker YBCO films produced by a BaF2 ex situ process, this is not true. Using electron backscatter diffraction combined with ion milling, we have been able to map the evolution of the YBCO grain structure and compare it to the underlying template in several coated conductors. For thin (≤0.5 μm) YBCO films deposited on rolling-assisted biaxially textured substrates (RABiTS), the YBCO GBs nearly directly overlap the substrate GBs. For 0.7–1.4 μm YBCO films, the GBs were found to meander along the substrate GBs and along the sample normal, with displacements several times the film thickness. In very thick films (2.5–2.9 μm), the YBCO grains can completely overgrow substrate grains and GBs, resulting in a substantial disconnection of the YBCO and substrate GB networks. Similar behavior is found for BaF2 ex situ YBCO films on ion-beam-assisted deposition-type templates. The ability of the YBCO to overgrow substrate grains and GBs is believed to be due to liquid-phase mediated laminar grain growth. Although the behavior of the YBCO GB networks changes with YBCO film thickness, the samples maintained high critical current density (Jc) values of >2 MA/cm2 for films up to 1.4 μm thick, and up to0.9 MA/cm2 for 2.5–2.9-μm-thick films.

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