Pulsed Laser Deposition of YBa2Cu2O7−δ for Coated Conductor Applications: Current Status and Cost Issues

Abstract

INTRODUCTIONAmongst the numerous techniques currently being tested for the fabrication of coated conductors (i.e. high-temperature superconducting oxides deposited onto metallic tapes), pulsed laser deposition (PLD) plays a prominent role. Recent results from groups in the United States (e.g. Los Alamos National Laboratory), Europe (e.g. University of Göttingen), and Japan (e.g. Fujikura Ltd.) are most promising, yielding record numbers for J c and I c .As a method for depositing films of complex materials, such as the high-temperature superconductors (HTS) relevant to this chapter, PLD is well established and conceptually simple. Issues that have kept PLD from becoming a successful technique for devices and optical materials, namely particulate formation and thickness non-uniformities, are much less of a concern in the fabrication of HTS tapes. Nevertheless, the approach still presents ongoing challenges in the fundamental understanding of the laser-target interaction and growth from the resulting energetic plasma plume. Numerous issues related to the scale-up, control, reproducibility, and economic feasibility of PLD remain under investigation.It is clearly beyond the scope of this short chapter to give a complete treatise of such a complex subject -fortunately, several excellent reviews have already been published. 1-3 It is thus the intent of the author to introduce PLD only briefly and with a strong focus on HTS deposition, summarizing the most important developments and referring the reader to the numerous cited works. A strong emphasis is placed on issues related to scale-up.Finally, it is the goal of this chapter to introduce a preliminary cost-analysis of PLD for coated conductor fabrication. While an attempt to calculate the total cost of fabricating a length of superconducting tape would be beyond the scope of this chapter (and beyond our current knowledge of numerous issues), we can present a rather detailed analysis of the 2 cost of laser operation. The point, of course, is not to show that PLD is either cheaper or more expensive than other techniques -in fact, for most other techniques, which have not been successfully applied to long length fabrication, such a calculation cannot yet be made. It is illustrative, for example, to consider that in an industrial setting, more meters of coated tape will have to be produced per day than some other methods have produced in their entire history, and that therefore many reliability issues (including mean-time between failure of equipment) have not been addressed for many of the approaches described in this book. It is the maturity of industrial laser technology combined with the maturity of the PLD process that allows us to estimate these costs for this technique.

Comparative study of CSD-grown REBCO films with different rare earth elements: processing windows and T c

“…improvement beyond YBCO, when years of YBCO research have passed [1][2][3][4][5][6][7][8][9][10][11]?…”

Field, temperature, and angle dependent critical current densityJc(H,T,θ) in coated conductors obtained via contact-free methods

“…Furthermore the induced currents, which produce a large signal, are selflimiting; in transport studies, these conditions often require large injected currents that can produce self-heating at the contacts, as well as the possibility of 'burning out' a high value sample. By accounting for the large difference in effective electric field criteria between transport and these contact-free magnetic methods, good consistency in results for J c (θ ) is obtained [18].…”

Pulsed electron deposition of fluorine-based precursors for YBa2Cu3O7−x-coated conductors

“…Furthermore, with the exception of a recently introduced approach where powders of complex oxides are continuously fed onto and evaporated from a rotating copper plate [24], each element to be deposited requires an independently controlled source, making the addition of dopants or the alloying between multiple complex compounds rather cumbersome. In contrast, PED uses a single, solid source of the mixed starting material, yet relies on equipment that is much simpler than the comparatively expensive excimer lasers [25] used in PLDan approach that would otherwise offer the same advantages.…”