resumo
Superconducting polycrystalline BSCCO fibers of 2: 2: 1: 2 nominal composition were grown by the electrically assisted laser floating zone (EALFZ) technique. An electric current density of 2.1 A cm(2) was applied through the solid/liquid (S/L) interface. A net effect of the fiber diameter on the as-grown microstructure and on the final superconducting properties is observed. A higher critical current density (similar to 2520 A cm(2)) results for the thinner fibers (phi = 1.7 mm) comparing to the value (similar to 1065 A cm(2)) found for the wider ones (phi = 2.5 mm). The steep axial thermal gradient at the S/L interface in the thinner fibers is responsible for its superior texture degree, a crucial parameter for improved current transport properties. Moreover, a Cu-free Bi(x)(Sr, Ca)(y)O(z) phase crystallizes preferentially from the melt in the wider fibers, acting as obstacles to the current flux. (C) 2008 Elsevier B. V. All rights reserved.
palavras-chave
O SUPERCONDUCTING FIBERS; MICROSTRUCTURE; BI2SR2CACU2O8; RODS
categoria
Chemistry; Materials Science; Physics
autores
Carrasco, MF; Silva, RA; Silva, NJO; Silva, RF; Vieira, JM; Costa, FM
nossos autores
Joaquim Manuel Vieira
Professor(a) Jubilado(a)
Nuno João Silva
Investigador Principal
Rui Ramos Ferreira e Silva
Professor associadoGrupos
G2 - Materiais Fotónicos, Eletrónicos e Magnéticos
G3 - Materiais Eletroquímicos, Interfaces e Revestimentos
agradecimentos
The financial funding from the FCT Project PTDC/CTM/66195/ 2006 and Brazilian Agency CAPES are gratefully acknowledged by the authors.