Critical current density enhancement in YBa2Cu3O6.8 films on buffered metallic substrates

Abstract

A transition buffer, consisting of subbuffers grown at different temperatures, was used to enhance the crystallinity and the transport properties of YBa2Cu3O6.8 (YBCO) films on metallic substrates. Films were fabricated using in situ laser deposition and were strongly c-axis oriented. Critical temperature of 87 K and critical current density of 3×104 A/cm2 at 77 K were obtained for a 0.5-μm-thick YBCO film with a 0.2 μm transition yttrium- stabilized ZrO2 buffer layer. Also, the magnetic field dependence of Jc could be enhanced by using Pt-coated metallic substrates.

Transport properties of magnetic field/liquid assisted textured YBa2Cu3O7−x thick films

“…The transport properties of MFLAT Y123 thick films are similar to those reported for Y123 thin films deposited on polycrystalline substrates, which have J ct values between 10 3 and 10 4 A/cm 2 at 77 K, 0 T, 15,16 but are far below those reported for biaxially aligned Y123 films, where J ct Ͼ10 5 A/cm 2 at 77 K, 0 T. 7,8 Such observations can be attributed to the lack of azimuthal ordering of the in-plane a and b axes in uniaxially aligned films. Dimos et al 17,18 have shown that when in-plane misorientation angles exceed a few degrees between neighboring Y123 grains, their boundaries have the properties of Josephson weak links.…”

Biaxially Textured IBAD-MgO Templates for YBCO-Coated Conductors

“…An order of magnitude improvement in J c values was realized for caxis-textured YBCO films on the YSZ-buffered metals ( J c Յ 3 ϫ 10 4 A/cm 2 at 77 K). [21][22][23] However, these fiber-textured YBCO films had J c values two orders of magnitude lower than highly biaxially textured YBCO/YSZ films deposited on single-crystal (SXAL) Si or GaAs substrates ( J c Ͼ 10 6 A/cm 2 at 77 K). [24][25][26] The polycrystalline YBCO results corroborated earlier studies by Dimos et al 27 of large reductions in intergranular J c values across single high-angle grain boundaries.…”

High temperature superconductor (HTS) wires and tapes

“…At the same time, high critical current densities of 5 MA/cm 2 were routinely achievable in high-quality epitaxial thin fi lms on single crystal substrates (Roas et al 1990). Use of thin-fi lm YBCO to fabricate tapes was initially explored using nickel alloy substrate and pulsed laser deposition (PLD) (Narumi et al 1991). Employment of expensive silver was nearly eliminated and diffusion of cations from the metal substrate was avoided by use of buffer layers such as yttria-stabilized zirconia (YSZ) between the substrate and the superconductor fi lm.…”