Superconducting Glass-Ceramic Fine Rods in Bi₁Ca₁Sr₁Cu₂Al_0.5O_x Prepared under a Temperature Gradient –T_c and the Texture of Specimen–

Abstract

Fine glass rods (dia. 1∼2 mm) in Bi 1 Ca 1 Sr 1 Cu 2 Al 0.5 O x prepared by pumping up the melt at 1150°C into SiO 2 glass tubes were reheated to 845°C according to a given procedure under a temperature gradient (≈30°C/mm) or under no temperature gradient. The incorporated Al enhanced the glassification. In the former specimen crystals grew well to become much larger, and impurity Al was excluded from the superconducting phases on crystallization under a temperature gradient to form the aluminous fibers; the T c (zero) is ≈80 K and a shoulder appears around 110 K.