Resum

This thesis is divided in six chapters. In the first one, we expose an amenable brief introduction to the YBCO compound, as well as to the CSD method. Then, in the second chapter we describe briefly the experimental techniques used for the physical

characterization of the CSD thin films presented in this work. The results, chapters 3, 4 , 5 and 6, are presented in two parts: Part I reports many aspects governing the growth mechanisms of CSD films, in particular the identification of those factors controlling the evolution of microstructures, which remain poorly established in comparison with vacuum deposited films. We give first an account of the evolution from a partially oriented granular microstructure to a dense epitaxial one in CeO2 films deposited from chemical solutions (chapter 3), and second the microstructural evolution of YBCO from trifluoroacetate precursors, which follow a complex compositional trajectory (chapter 4). In part II the microstructure of TFA-YBCO thin films with high critical current densities is analysed. We depict intrinsic structural defects occurring within YBCO films, focusing in extended defects which can lead to strong flux-pinning and high critical current density (chapter 5). The microstructure of TFA-YBCO films with artificial defects has been also studied (chapter 6). The inclusion of BaZrO3 results in strong increase of the critical current density, demonstrating that chemical solution growth is a very flexible methodology to nanostructure YBCO films and coated conductors.

Finally, we present the general conclusions of this study.

La difusió d'aquesta tesi per mitjà del servei TDX ha estat autoritzada pels titulars dels drets de propietat intel.lectual únicament per a usos privats emmarcats en activitats d'investigació i docència. No s'autoritza la seva reproducció amb finalitats de lucre ni la seva difusió i posada a disposició des d'un lloc aliè al servei TDX. No s'autoritza la presentació del seu contingut en una finestra o marc aliè a TDX (framing).

Aquesta reserva de drets afecta tant al resum de presentació de la tesi com als seus continguts. En la utilització o cita de parts de la tesi és obligat indicar el nom de la persona autora.