Thickness effect of La₂Zr₂O₇single buffers on metallic substrates using pulsed laser deposition for YBa₂Cu₃O_7−δ-coated conductors

Abstract

In the present work, the single buffer layers of La 2 Zr 2 O 7 (LZO) with different thicknesses were prepared using pulsed laser deposition (PLD) on highly textured Ni-5 at.%W tapes for YBa 2 Cu 3 O 7−δ -coated conductors. The highly textured LZO layers are obtained on the metallic substrates, making the subsequent epitaxial growth of superconducting YBa 2 Cu 3 O 7−δ layers feasible. The superconducting transition temperature increases as the LZO thickness increases up to 240 nm, achieving a value of T c of more than 92 K with a narrow transition width less than 1 K. Inductive measurement reveals that the critical current density (J c ) reaches 0.77 MA cm −2 at 77 K in self-field, showing that the single buffer of LZO is comparable to standard buffer architectures such as CeO 2 /YSZ/Y 2 O 3 or CeO 2 /LZO. This implies that the LZO as a single buffer layer is promising for the simplification of the preparation process, leading to cost-effective coated conductors.

Reel-to-Reel Deposition of Reactively Sputtered LaZrO Buffer Layers on Textured NiW Tapes for YBaCuO Coated Conductors

“…The four symmetric peaks in the pole figures suggest that the LZO has a strong cube texture with an epitaxial relationship of (001) 110 LZO (001) 100 Ni . The in-plane full width at half maximum value (FWHM) for ϕ-scans of LZO (222) peak is round 6.5°, being comparable with samples prepared by PLD [10,11]. Figure 3 shows the AFM image of LZO film with the thickness of 220 nm.…”

“…LZO used as the buffer layer material has a small lattice mismatch with RE123 (1.05%), and provides a good barrier against O 2 diffusion and achieve epitaxial growth on NiW tapes [8,9]. We recently investigated the epitaxial growth of LZO [10] and thickness effect of single LZO buffer on performance of related coated conductor using pulsed laser deposition (PLD) [11]. The technique is well known as a predominant technique for fabricating films, but not enough for fast and low cost in scale-up processing.…”

Properties of YBa2Cu3O7−δ Superconducting Films on Sr2YSbO6 Buffer Layers

“…Some of the highest critical current densities at 77 K and highest film uniformities have been achieved in YBa 2 Cu 3 O 7−δ films grown on commercially available (1 0 0) SrTiO 3 substrates (Huhne et al, 2006;Jia et al, 2002;2003;Ortiz-Diaz et al, 2004a;Sathyamurthy et al, 2003;Varanasi et al, 2008;Wang et al, 2005;Wee et al, 2005;Wu et al, 2005;Ying et al, 2009). However, SrTiO 3 is fairly expensive, has high dielectric constant, and undergoes phase transition at ∼ 110 K. LaGaO 3 with ∼ 0.5% mismatch it is neither cheap nor twin free (Cyrot & Pavuna, 1992).…”

“…In this context, the preparation of bi-axially textured substrates and subsequent epitaxial buffer layers is very important for the realization of long-length YBa 2 Cu 3 O 7−δ coated conductors. The buffer layer should not only satisfy chemical stability, but structural matching with YBa 2 Cu 3 O 7−δ as well because the alignment of the superconductor is required for high Jc values (Foltyn et al, 2007;Ying et al, 2009). …”

“…However, most of them are really multilayer architectures, which significantly increase the complexity as well as the cost of production (Ying et al, 2009). Therefore, the development of a single buffer layer is of great interest, as this might simplify the preparation process and lead to a more cost-effective fabrication of coated conductors.…”