Wires and tapes based on the High Temperature Superconductors (HTSC) REBa2Cu3Ox (RE = Y, Gd etc.) have the potential to improve power electric systems dramatically in respect to low loss design and high power density. The development of these HTSC power applications like motors, transformers or cables require a high current carrying and low cost basic conductor that can be used in magnetic fields. Currently HTSC coated conductors (CC) are under development as a very promising 2nd generation HTSC tape that is able to fulfil all the necessary requirements. The CC approach is based on depositing epitaxially a HTSC film onto a highly biaxially textured buffered metal tape. A very sharp biaxial texture is required since already low-angle grain boundaries reduce significantly the overall critical current density. Very good textures, and therefore also nearly single crystalline Jc-values exceeding 106 A/cm2 at 77 K and in zero field, can be obtained either on biaxially textured buffer layers obtained by ion beam assisted film deposition (IBAD) or inclined substrate desposition (ISD). Alternatively, buffered Ni-W metal tapes with a sharp cube texture due to recrystallization after heavy cold rolling can be used as templates. Since the main application sector of these tapes will be connected with magnetic fields, further improvements of the intrinsic HTSC pinning properties in films used for CCs are required. This can be achieved by controlled introduction of nano-scaled artificial defects into the highly textures Y123 film matrix.
The main focus of our work during the last years is devoted to the growth of thick YBa2Cu3O7-x (YBCO) layers with artificial pinning centers on textured templates provided by industrial suppliers. These superconducting layers are typically grown by pulsed laser deposition using mixed targets with BaHfO3 (BHO) or Ba2Y(Nb,Ta)O6 (BYNTO) additions. As a result, a complex defect structure with YBa2Cu4O8 intergrowths, Y2O3 precipitates and BHO/BYNTO nanocolumns with a fan-shaped structure is observed in TEM investigations, which influences the Jc(B,θ) behavior and can be used to tune the superconducting properties. Additionally, significant efforts were directed to study the influence of granularity on the local current transport in YBCO layers prepared on such technical substrates. Therefore, high resolution EBSD measurements were performed on superconducting YBCO layers with different thickness prepared on Ni-W tapes as well as on IBAD based templates and compared to local Hall scans.
P. Pahlke, M. Lao, M. Eisterer, A. Meledin, G. Van Tendeloo, J. Hänisch, M. Sieger, A. Usoskin, J. Strömer, B. Holzapfel, L. Schultz, R. Hühne
Reduced Jc anisotropy and enhanced in-field performance of thick BaHfO3-doped YBa2Cu3O7-δ films on ABAD-YSZ templates
IEEE Trans. Appl. Supercond. 26 (2016) 6603104.
M. Sieger, P. Pahlke, J. Hänisch, M. Sparing, M. Bianchetti, J. MacManus-Driscoll, M. Lao, M. Eisterer, A. Meledin, G. Van Tendeloo, R. Nast, L. Schultz, B. Holzapfel, R. Hühne
Ba2Y(Nb/Ta)O6-doped YBCO films on biaxially textured Ni-5at.% W substrates
IEEE Trans. Appl. Supercond. 26 (2016) 7500305.
B.H. Stafford, M. Sieger, O. Troshyn, R. Hühne, J. Hänisch, M. Bauer, B. Holzapfel, L. Schultz
Pinning centers in ISD-MgO coated conductors via EB-PVD
IEEE Trans. Appl. Supercond. 26 (2016) 6601105.
A. Kirchner, A. Winkler, S.M. Menzel, B. Holzapfel, R. Hühne
Surface acoustic waves – a new thin film deposition approach for coated conductors
IEEE Trans. Appl. Supercond. 26 (2016) 6602704.
P. Pahlke, M. Sieger, P. Chekhonin, W. Skrotzki, J. Hänisch, A. Usoskin, J. Strömer, L. Schultz, R. Hühne
Local orientation variations in YBCO films on technical substrates – a combined SEM and EBSD study
IEEE Trans. Appl. Supercond. 26 (2016) 7201505.
L. Opherden, M. Sieger, P. Pahlke, R. Hühne, L. Schultz, A. Meledin, G. Van Tendeloo, R. Nast, B. Holzapfel, M. Bianchetti, J.L. MacManus-Driscoll, J. Hänisch
Large pinning forces and matching effects in YBa2Cu3O7-δ thin films with Ba2Y(Nb/Ta)O6 nano-precipitates
Sci. Reports 6 (2016) 21188.