Structure of superconducting fibers prepared by laser-heated pedestal growth method

Abstract

Superconducting fibers have drawn great attention because of the latent prospect for applications. Fibers of superior quality were obtained by means of the laser-heated pedestal growth (LHPG) method. For LHPG method a fine laser beam is focused at the “source rod” made of raw material so that a small molten zone is formed on its upper end. Then a seed crystal is introduced into the melt and drawn from it to grow crystalline fibers. In this paper the structure of bismuth based Bi-Sr-Ca-Cu-O and Bi-Pb-Sr-Ca-Cu-O superconducting fibers prepared by LHPG is reported. The values of Tc for the two kinds of fibers are 85k and 108k respectively. The critical current density Jc can reach 5150A/cm2. The diameters of fibers are ranged from 35μm-200μm. The thin fibers are flexible.Fig.1 shows the transition region between the source rod (R) and the LHPG fiber (G). It indicates that the source crystal first melts and then recrystallizes along a certain cry stenographic direction.