Tapas Chaudhuri

Electrodeposited Biaxially Textured Buffer Layer for YBa2Cu3O7 − δ (YBCO) Superconductor Oxide Films

Nonvacuum electrodeposition was used to prepare biaxially textured CeO 2 and Sm-doped CeO 2 coatings on Ni-W substrates. The samples were characterized by X-ray diffraction (including θ/2θ, pole figures, Ω scans, and Φ scans), atomic force microscopy, and Auger electron spectroscopy (AES). Pole-figure scans show that electrodeposited CeO 2 and Sm-doped CeO 2 on textured Ni-W (3 atom %) is cube textured. Full width at half maximum values of the ω and Φ scans of the electrodeposited layers were better than those of the Ni-W base substrates, indicating improved biaxial texturing of the electrodeposited layers. AES analysis of the YBCO/CeO 2 /yttria-stabilized zirconia/electrodeposited CeO 2 /Ni-W revealed that Ni interdiffusion was completely stopped at the first electrodeposited CeO 2 laver.

Electrodeposited Biaxially Textured Ni Layer for YBCO Superconductor Oxide Films

Nonvacuum electrodeposition was used to prepare biaxially textured Ni coatings on Ni-W substrates. The samples were characterized by X-ray diffraction (including θ/2θ, pole figures, omega scans, and phi scans), and atomicforce microscopy. Pole-figure scans show that electrodeposited (ED) Ni on textured Ni-W (3 atom %) is 99.3% cube textured. Full width at half-maximum values of the ω scan and Φ scan of the electrodeposited Ni layers were comparable to the Ni-W base substrates, indicating good biaxial texturing. The buffer structures were completed on these types of seed ED-Ni layers by pulsed-laser-deposited (PLD) CeO 2 /YSZ/CeO 2 . We obtained a critical current density of 1.8 MA/cm 2 at 75.2 K in 600 Gauss magnetic field for PLD YBa 2 Cu 3 O 7 - δ /CeO 2 /YSZ/CeO 2 /ED-Ni/Ni-W.

Electrodeposited Biaxially Textured CeO2 and CeO2:Sm Buffer Layer for YBCO Superconductor Oxide Films

Nonvacuum electrodeposition was used to prepare biaxially textured CeO2 and Sm‐doped CeO2 coatings on Ni‐W substrates. The samples were characterized by X‐ray diffraction (including θ/2θ, pole figures, omega scans, and phi scans), atomic force microscopy (AFM), Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Full‐width at half‐maximum values of the ω scan and φ scan of the electrodeposited layers were better than those of the Ni‐W base substrates, indicating improved biaxial texturing of the electrodeposited layers.

Development of Electrodeposited Iridium as a Buffer Layer for YBCO Superconductors

Electrodeposition (ED) is a potentially low-cost, non-vacuum, high-rate deposition process that can easily deposit uniform film on large non-planar substrates. In this paper, we report on successful biaxial textured electrodeposition of Ir on Ni-W substrates. Ir metal is well known for its excellent oxidation and corrosion resistance among platinumgroup elements; also, the lattice mismatch of cubic Ir is very close to that of CeO 2 and Ni. The films were deposited in a vertical cell in which the electrodes (both working and counter) were suspended vertically from the top of the cell. The ED experiments were performed at 65°C without stirring the solution. The ED precursors were prepared at about -1.2 V from 2 to 15 minutes on Ni-W, where the Pt counter and Pt pseudo-reference electrodes were shorted together. To qualify the electrodeposited Ir buffer layer, a CeO 2 /YSZ/CeO 2 and YSZ/CeO 2 buffer structure was later deposited on ED Ir-coated Ni-W substrates by pulsed-laser deposition. The ED Ir/metal substrates were first heated at 800°C in 0.5 mTorr of forming gas, and then a CeO 2 seed layer was deposited in 180 mTorr of forming gas. Subsequently, YSZ and CeO 2 layers were deposited sequentially in 0.1 mTorr of oxygen.

Pulsed-Laser Deposition of Biaxially Textured YSZ/CeO 2 Films on Electrodeposited Ir/Ni-W Tapes for YBCO Superconductors

Iridium film is a potential candidate as a buffer layer for yttrium barium copper oxide (YBCO) coated conductors. Pulsed laser deposition (PLD) of biaxially textured CeO 2 /yttrium stabilized zirconium oxide (YSZ) layers on electrodeposited Ir/Ni-W is reported. Biaxial texturing is obtained by deposition of a YSZ seed layer at 800°C in 10 -6 Torr vacuum. X-ray diffraction (XRD) studies of Θ-2Θ and pole figure confirmed in-plane out-of-plane biaxial texturing with Δφ = 6.5° and Δω = 8°. Atomic force microscopy (AFM) revealed a surface with roughness of about 3 nm.