Effect of the amount of tungsten on the superconducting properties of Ni-W substrates based coated conductors.*

One of the main challenges in the use of high temperature superconducting wires, the YBa₂Cu₃O_7-δ (YBCO) coated conductors (CC) in electric power applications is the amount of dissipation or loss. Ni-W alloys are used as substrates for rolling assisted biaxially textured substrate (RABiTS) tapes because of their comparably low loss and ease of manufacturing. In this work, we have determined the amount of ferromagnetic loss in a series of biaxially textured Ni_1-xW_x materials with compositions x = 5 and 9 at.% W. We also measured the critical current density J_c in two different samples of coated conductor; one fabricated with the Ni-5at.%W substrate and the other with the Ni-9at.%W substrate. The aim is to determine if the type of substrate used will influence the amount and the property of J_c measured. While the Ni-5at.%W  shows a higher ferromagnetism (and loss), the J_c measured in both CC is fairly similar. The field and temperature dependence of the J_c  in the two samples is also analyzed.