EFFECT OF AG2O ADDITIVE ON MICROSTRUCTURE AND SUPERCONDUCTIVITY OF THE TL2BA2CA2CU3OY COMPOUND

A series of Ag-doped Tl2Ba2Ca2Cu3Oy superconducting Oxides were prepar ed by a solid-state reaction and the influence of Ag2O content, with a varying molar ratio which ranged from 0 to 1.0, was also investigated . The normal-state resistance of the samples decreased with an increas e in the content of Ag2O additive, while the critical superconducting temperatures of the Ag-doped samples increased once the Ag2O content w as increased. The doping of the silver oxide was indicated from the re sults of the x-ray diffraction pattern to be favorable to the formatio n of the three CuO layers with a high-T(c) phase T12Ba2Ca2Cu3Oy. The d iamagnetic Property of the samples was also confirmed by the magnetic measurements to become enhanced by doping with silver oxide. The plate like grains of Tl2 Ba2CaCu2Oy phase Were Observed from scanning electr on micrographs to be primarily present in the undoped sample, while th e amount of the needlelike Tl2Ba2Ca2Cu3Oy grain increased with an incr ease in the doping amount of Ag2O.