Grain alignment and transport properties of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8 /grown by laser-heated float zone method

A single-phase Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ bulk superconductor (T/sub c/ approximately=82 K) has been grown by the laser-heated float zone method. The samples are highly textured with the grains. typically 100 mu m diameter and 0.5-cm long, and elongated along the crystal a-axis. which is the preferred growth direction. X-ray analysis and transport measurements indicate that all three principal axes (a, b, c) are oriented from grain to grain. The upper limit of the misalignment between the grains is estimated to be less than 2 degrees from the measured anisotropy ratio. The critical current density for such highly textured polycrystalline samples is anisotropic and limited mainly by the weak links at the grain boundaries. The grain boundary effects are examined on the basis of the measured temperature and magnetic field dependence of the critical current.