Pd layer on cube-textured substrates for MOD-TFA and PLD YBCO coatedconductors

Abstract

Pd films were deposited on rolling assisted biaxially textured substrate(RABiTS) Ni–5 at.% W in order to exploit the Pd effect of the texturesharpening with respect to that of the substrate, for the development ofYBa2Cu3O7−x (YBCO)coated conductors. The Pd sharpening effect was relevant in the out-of-plane direction where the reductionfor the ω-scans’ full width at half maximum (FWHM) ranged from 55 to 65%,depending on the substrate roughness. The obtained minimum valuesof the FWHM in the transverse rolling direction of the (002) Pdω-scan and in the(111) Pd ϕ-scanwere of about 2.5° and 5°,respectively. The CeO2/YSZ/CeO2 (YSZ is Y2O3-stabilised ZrO2) heterostructure of the buffer layer was developed by pulsed laser deposition(PLD). In order to transfer the sharp orientation of the Pd film, both the seedCeO2 layer and the YSZ layer were deposited at low temperatures(450 °C), lowenough to avoid Pd/Ni–W interdiffusion. The YBCO, films deposited by both PLD and metal-organicdeposition (MOD) using metal trifluoroacetate acid (TFA), exhibited rolling direction (005)ω-scan and the (113)ϕ-scan FWHMvalues of about 2° and 5°, respectively. In spite of the complete interdiffusion between Ni and Pd duringthe YBCO film deposition, the coated conductors exhibit good adherence, aswell as a smooth and crack-free surface. A zero-resistance critical temperature(TC0) of 90.8 K for the MOD-TFA YBCO films and critical current-density(JC) upto 2.2 MA cm−2 at 77 K and self-field for PLD YBCO films have been obtained.