Abstract:

Textured samples having composition of YBa2Cu3O7-d were prepared by using a novel technique of heating the samples in a thermal gradient which varies linearly between 930-950 oC over a distance of 5 cm. The samples were characterized by X-ray powder diffraction analysis, temperature dependent resistivity and magnetic susceptibility measurements, and scanning electron microscopy. XRD analysis shows that sample heated between 930-935 oC has tetragonal symmetry and all other three samples show orthorhombic symmetry. Samples heated in temperature gradient of 935-945 oC aligned along the c-axis. The orthorhombic samples exhibited zero resistance above 86K with short transition width and samples heated in the temperature range of 930-935 oC was non-superconducting down to 80 K. Susceptibility measurements also confirms the same Tc values for the superconducting samples. The orientation of crystals and alignment of grains was observed by SEM images and investigated by XRD patterns. The maximum texture alignment of the YBa2Cu3O7-d superconducting grains is obtained in a thermal gradient of 935-945 oC.

Keywords: