Relação entre o transporte elétrico e a estrutura de poros no sistema YBa2Cu3O7

• Autor(a) principal: Piumbini, Cleiton Kenup
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/7479
• topic: Sintering Conditions; Transport Critical Current density; Pore Structure; Corrente Crítica de transporte; Porosidade; Condições de Síntese; Física; Supercondutividade; Porosidade; Antimônio; Ítrio; 53

The principal objective of this thesis is the study of the relationship between the transport critical current density and the pore structure in YBa2Cu3O7-y bulk samples. In order to perform the experimental work samples of two different systems were prepared. The first sintered system was (YBa2Cu3O7-y)1-x(Sb2O3)xwhile the second one was obtained through the use of different sintering conditions. The samples were characterized through X-ray, magnetic and transport critical current density measurements, besides N2 sorption analysis. In both systems, the doping and the different sintering conditions modified the pore structure of the samples. For the (YBa2Cu3O7-y)1-x(Sb2O3)x system the transport critical current density did not depend on the pore structure, while in the second system this parameter showed a strong correlation with the principal features of the pore structure. In order to better understand the correlation between the electric transport and the structural properties of the specimens, it was developed a computational simulation aiming to incorporate the principal elements of the granular structure of ceramic samples. To this end, the granular simulated granular structure was obtained by a tessellation of the space through the Voronoi technique. The results of computer simulations show that it is possible to capture the dependence of the critical current density of transport with the relevant quantities to different systems studied in this thesis. Finally, this work shows the importance of controlling the pore structure in order to optimize the electrical properties of ceramic superconductors cuprates, which is transcendent to possible technological applications of these systems.