Thickness control of solution deposited YBCO superconducting films by use of organic polymeric additives
- PDF / 348,307 Bytes
- 9 Pages / 585 x 783 pts Page_size
- 31 Downloads / 162 Views
e show that the thickness of yttrium–barium–copper–oxide (YBCO) superconducting films grown from trifluoroacetate precursors can be strongly modified using polymeric additives, while deposition conditions by spin or dip coating remain unchanged. A screening of different families of organic additives has been performed, and the best results have been achieved using polymers having an oxygen functionalized backbone. Two different polymeric additives, polyvinyl pyrrolidone (PVP) and poly(ethylene glycol) (PEG), have been more thoroughly investigated, and thermal analysis suggests that PEG is the most promising alternative because the pyrolysis step of the new complex precursors remains sharp and narrow and hence the final homogeneity of the film is preserved. The combination of anhydrous trifluoroacetic acid (TFA) solutions and poly(ethylene-glycol) (PEG8000) as additive can produce an increase of the YBCO film thickness up to 300%, while keeping a fast pyrolysis process and high critical current densities. I. INTRODUCTION
Superconducting power systems are regarded as a very promising application of high-temperature oxide superconductors. From this viewpoint, high-temperature superconducting thin/thick films, especially YBa2Cu3O7−x (YBCO), deposited on various substrates, have attracted much attention in recent years because of their unique properties of high epitaxial film, high critical temperature (Tc), and high critical current density (Jc). Physical deposition techniques, such as pulsed laser deposition (PLD) methodology,1–4 sputtering,5 metal evaporation,6 or BaF2 process7 and chemical deposition methods such as metalorganic chemical vapor deposition (MOCVD)8 or metalorganic deposition (MOD)9 are effectively used to produce thick films. In all cases, it is desirable to achieve great film thickness without decreasing the critical current density, an issue that is still under investigation in all the different deposition methodologies. The implementation of low-cost deposition techniques for high critical current YBCO-coated conductors is one of the major objectives to achieve widespread use of superconductivity in power applications. Chemical deposition techniques appear to be a very promising route to achieve this goal.10 The use of trifluoroacetic (TFA) precursors,11 avoiding the formation of deleterious BaCO3 a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2007.0296 2330
J. Mater. Res., Vol. 22, No. 8, Aug 2007
phase, has already been shown to be very competitive and has to be considered one of the most valuable alternatives for achieving low-cost chemically based coated conductors.12–16 The investigation of methodologies allowing tuning and control of film thickness using the TFA-MOD process is a very important issue to enhance the industrial scalability of the process. A close analysis and comprehension of the relationship among metalorganic precursor composition, solution deposition methodology, pyrolysis process, and growth conditions are required for this purpose.
Data Loading...
