Innovative HTS coated conductors for in-field applications

International superconductor research is increasingly focusing on "coated conductors", the "second generation" of high temperature superconducting (HTS) conductors. Coated conductors are intended to replace wires and tapes, manufactured from the Bi-based superconducting compound Bi 2223, since the superconducting properties of the bismuth based materials deteriorate rapidly in external magnetic fields. The coated conductors currently under investigation employ yttrium-barium cuprates (YBCO) as the superconducting material. They are studied and developed into "practical" materials by several research groups worldwide. Although enormous progress and very promising results have been achieved during the past few years, the development efforts are still far from complete. The buffer and the superconducting layer for the current version of coated conductors are prepared by high-vacuum techniques, such as pulsed laser or ion beam assisted deposition. In view of the complex nature of these fabrication processes and the associated high production costs, strong activities aiming at an "all-chemical" production of buffers and superconductors have emerged recently. In view of this strong focusing of research activities on yttrium-barium-cuprate as the superconductor material, practically no activities are currently under way to develop substrate - (buffer) layer - superconductor composites of other high temperature superconducting compounds, especially of the thallium based superconductors, despite the well established excellent superconducting properties of these compounds at high temperatures and magnetic fields. This proposal focuses on the fabrication of composite tapes (coated conductors) under ambient pressure by a combination of wet chemical - solid state reactions, to avoid costly high vacuum techniques, and on their detailed characterization in the superconducting state by a partner institute in Vienna. Protective layers on Ni-Cr or Fe-Ni- Cr will be electro-deposited on suitable Ni or stainless steel substrates from aqueous and non-aqueous systems. Novel substrate - buffer layer combinations will also be investigated. The buffer layers will be applied by different techniques, such as gel methods, dip or spray coating from aqueous and non-aqueous systems. The superconducting layer will be mainly thallium based. The main objective of this is to arrive at a composite material, consisting of a low price substrate with a suitable buffer layer and a superconducting layer, which has very high critical currents at 77 K and in high magnetic fields.

International superconductor research is increasingly focusing on "coated conductors", the "second generation" of high temperature superconducting (HTS) conductors. Coated conductors are intended to replace wires and tapes, manufactured from the Bi-based superconducting compound Bi 2223, since the superconducting properties of the bismuth based materials deteriorate rapidly in external magnetic fields. The coated conductors currently under investigation employ yttrium-barium cuprates (YBCO) as the superconducting material. They are studied and developed into "practical" materials by several research groups worldwide. Although enormous progress and very promising results have been achieved during the past few years, the development efforts are still far from complete. The buffer and the superconducting layer for the current version of coated conductors are prepared by high-vacuum techniques, such as pulsed laser or ion beam assisted deposition. In view of the complex nature of these fabrication processes and the associated high production costs, strong activities aiming at an "all-chemical" production of buffers and superconductors have emerged recently. In view of this strong focusing of research activities on yttrium-barium-cuprate as the superconductor material, practically no activities are currently under way to develop substrate - (buffer) layer - superconductor composites of other high temperature superconducting compounds, especially of the thallium based superconductors, despite the well established excellent superconducting properties of these compounds at high temperatures and magnetic fields. This proposal focuses on the fabrication of composite tapes (coated conductors) under ambient pressure by a combination of wet chemical - solid state reactions, to avoid costly high vacuum techniques, and on their detailed characterization in the superconducting state by a partner institute in Vienna. Protective layers on Ni-Cr or Fe-Ni- Cr will be electro-deposited on suitable Ni or stainless steel substrates from aqueous and non-aqueous systems. Novel substrate - buffer layer combinations will also be investigated. The buffer layers will be applied by different techniques, such as gel methods, dip or spray coating from aqueous and non-aqueous systems. The superconducting layer will be mainly thallium based. The main objective of this is to arrive at a composite material, consisting of a low price substrate with a suitable buffer layer and a superconducting layer, which has very high critical currents at 77 K and in high magnetic fields.