N A N O M AT E R I A L S F O R E N E R G Y
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The key development for a fast market penetration is to fabricate long-length nanostructured conductors at low cost, mainly through chemical deposition methodologies. The most promising materials are at present the so called 2nd generation (2G) coated conductors, based on YBa2Cu3O7 (YBCO).
systems. In spite of the remarkable progress already achieved, there is still a large margin for improvement because the theoretical limits of these materials are still well above the achieved critical currents. It’s particularly essential to understand properly the relationship between nanostructure and vortex pinning properties.
The first goal has been to avoid the detrimental effect of grain boundaries on critical current density and this has already been achieved through clever methodologies to develop oxide epitaxial layers on metallic substrates while keeping structural control at the nanoscale. Industrial production of 2G conductors over km lengths has been already demonstrated although much more effort is still required to simplify their architecture and hence reduce the cost.
These conductors have demonstrated current densities 10 times higher than Cu and so the development of high power underground cables (5-7 times conventional wire power) is one of the closest priorities, together with Fault current limiters to reach a smarter grid allowing to integrate the renewable energies The worldwide roadmaps defined up to now suggests a progressive penetration of this new technology in the market of power systems in the next 10-20 years.
A second boost on performance of 2G superconductors has been recently demonstrated through the development of nanocomposite films and conductors. The goal here is to create a network of nanometric nonsuperconducting phases (nanodots, nanorods) within the superconducting matrix which pin vortices and hence increase the critical current at high temperatures and under high magnetic fields.
3. International publications (2007-2009) A selection of publications spanning all the fields mentioned before is reported here. •J. Gutiérrez, A. Llordés, J. Gázquez, M. Gibert, N. Romà, S. Ricart, A. Pomar, F. Sandiumenge, N. Mestres, T. Puig and X. Obradors. Strong isotropic flux pinning in solutionderived YBa2Cu3O7-x nanocomposite superconductor films. Nature Materials, 6 (2007), pp. 367-373.
Understanding the growth mechanisms of complex oxide nanocomposites and the influence of induced strain on the superconducting properties is one of the present bottlenecks for further development of materials with enhanced performance.
•B. E. Hardin, E.T. Hoke, P.B. Armstrong, J.H. Yum, P. Comte, T. Torres, J.M.J. Frechet, M.K. Nazeeruddin, M. Gratzel and M.D. McGehee Increased light harvesting in dye-sensitized solar cells with energy relay dyes. Nature Photonics, 3 (2009), pp. 406-411.
For the first time, the performance of these nanostructured superconductors has surpassed at 77OK those of low Tc superconductors at liquid He temperature.
•H. Gommans, T. Aernouts, B. Verreet, P. Heremans, A. Medina, C.G. Claessens, G Christian and T. Torres. Perfluorinated Subphthalocyanine as a New Acceptor Material in a Small-Molecule Bilayer Organic Solar Cell.
Very high magnetic fields are expected to be created for magnets (fusion), generation (wind energy), motors (ships) and energy storage 50