Fluctuation conductivity of polycrystalline Y1-xPr xBa2Cu3O7-delta superconductors

• Autor(a) principal: Jurelo,Alcione Roberto
• Data de Publicação: 2005
• Outros Autores: Araújo,Celmir Lupack de, Siqueira,Ezequiel Costa, Cantão,Maurício Pereira
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Journal of Physics
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332005000400001

We studied the effect of superconducting fluctuations on the electrical conductivity of granular samples of Y1 - xPr xBa2Cu3O7-delta superconductors, with x = 0.01, 0.03, 0.05, 0.07 and 0.10. Samples were prepared by the standard solid-state reaction technique, with two different types of calcination process, in air at 900 ºC ( x < 0.07 ) and in vacuum at 850 ºC ( 0.05 < x < 0.10 ). For the samples prepared in air, our results revealed a splitting of the bulk transition, denoted by T C1 and T C2, besides the coherence transition. It was observed fluctuation regimes above the highest transition ( T C1 ) and the lowest transition ( T C2 ). For the samples calcinated in vacuum and high concentrations of Pr, changes were observed in the critical region with chemical substitution of the Pr ion for the Y ion. In the regime of approach to the zero resistance state it was observed an occurrence of a coherence transition for all concentrations of praseodymium.