Chemical Solution Deposition of Oxide Buffer and Superconducting Layers for YBa(2)Cu(3)O(7) Coated Conductors

• Autores: Mariona Coll Bau
• Directores de la Tesis: Teresa Puig i Molina (dir. tes.), Xavier Obradors Berenguer (dir. tes.)
• Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2007
• Idioma: inglés
• Tribunal Calificador de la Tesis: Susagna Ricart Miró (presid.), Felip Sandiumenge Ortiz (secret.), Javier Rodríguez Viejo (voc.), Manuel Varela Fernández (voc.), Juan Pedro Espinós Manzorro (voc.)
• Materias:
  • Química
• Enlaces
  • Tesis en acceso abierto en:  TDX  DDD 
• Resumen

  • Since the discovery of high-temperature superconductivity (HTS) in cuprate materials, substantial efforts have focused on developing a high-current superconducting wire technology to fully exploit their fundamental current-carrying capability. YBa2Cu3O7 (YBCO) is the most promising material for HTS wires (second-generation coated conductors) because it has a very high potential to carry high currents at high magnetic fields operated with liquid nitrogen cryogenics (65-77K). One crucial requirement for the preparation of YBCO coated conductors with high critical current densities is the elimination of weak links between YBCO grains. Weak links in the high temperature superconductors are produced by grain boundaries that lead to a weak coupling between the superconducting grains and consequently to a reduction in the critical current density. Thus, the key is to prepare a textured substrate adequately buffered with oxide layers which transmit, totally or partially, the underneath structure to the superconducting layer. Presently, there are two main techniques for textured template fabrication: Rolling Assisted Biaxially Textured Substrates (RABiTS) and Ion Beam Assisted Deposition (IBAD). Among the various process used to prepare YBCO and buffer layers films, metalorganic decomposition (MOD) has recently emerged as a very competitive approach to cost-effective manufacturing process that allow to easily control precursor chemistry maintaining high electrical performance in the superconducting layer. The aim of this Thesis, is to fabricate all-chemical YBCO multilayered system, using trifluoroacetates (TFA) precurors for YBCO, with high critical current density to be further transferred on metallic substrates. It requires a tight control of the interface quality in the multilayered architecture, i.e. between a substrate, one or several buffer layers and the superconducting layer itself. Although the film and the substrate have similar structure, the film can undergo