T. Küçükömeroğlu

Superconducting properties of gold-diffusion doped BiPbSrCaCuO

Abstract The crystal structure and superconducting properties of the gold-doped BiPbSrCaCuO have been investigated using X-ray diffraction, scanning electron microscope and electrical measurements. Doping of BiPbSrCaCuO was carried out by means of gold diffusion from an evaporated layer onto pellets at the sintering. It was found that the diffusion doping of pellets by gold stimulates formation of the Bi (2 2 2 3) phase, increases critical temperature and critical current density (from 33 A cm −2 for undoped sample to 112 A cm −2 for gold-doped BiPbSrCaCuO). Improving of structure and superconducting properties was discussed on the base of model related with retarding of the precipitation processes under the gold-diffusion doping technique used.

Ag-doped 120 K YBa2Cu3O7- delta superconductors prepared by the flame-quench-melt-growth (FQMG) method

The effect of Ag-doping on the microstructure and physical properties of YBa2Cu3O7- delta superconductors prepared by a flame-quench-melt-growth (FQMG) process, was investigated. Pellets of YBa2Cu3O7- delta containing 0-30 weight percentage (wt.%) of Ag were quenched by LPG-O2 flame melting and then crushed to obtain powder which was compacted and then subjected to a melt-growth process. As a result of this process, large grained, textured YBCO material was produced. It was found that YBCO samples with 10 wt.% Ag doped showed a transition temperature of 120 K and further increasing the Ag content caused a decrease of transition temperature. Using this modified quench-melt-growth technique, the reaction between crucibles and material can be completely avoided during the preparation of the precursor materials.