Sintering characteristics of Y-Ba-Cu-oxide-Ag-x superconductors

The sintering characteristics of Y-Ba-Cu-oxide (YBCO)-Ag-x (x = 0 to 1.2) u sing thermomechanical analyzer were systematically investigated to understa nd the sintering mechanism of the metal superconductor composites. The addi tion of ag was observed to lower the sintering temperatures, and the appare nt densities of the sintered compacts increased with x from 0 to 0.6. A fur ther increase of x above 0.6 decreased the apparent densities of the sinter ed compacts. The presence of Ag globules in the YBCO-Ag compacts was observ ed by scanning electron microscopy and energy dispersive x-ray spectroscopy . The apparent activation energies for sintering of the powder compacts wer e estimated and observed to vary between 900 to 2000 kJ/mol. The formation of AgOx by absorbing oxygen from YBCO and sintering atmosphere possibly con trols the sintering and superconducting behavior, incorporation of Ag into the matrix modifies the weak-link characteristics from superconductor-insul ator-normal- superconductor (S-I-N-S) to superconductor-normal-superconduct or (S-NS) type.