Effect of sintering atmosphere on the weak-link behaviour of YBCO superconductors

Weak-link behaviour of YBa2Cu3Ox (1 2 3) superconductors sintered in different atmospheres are studied by measuring the variation of critical current densities (Jc) near the superconducting transition temperatures (Tc). The weak links are found to change from superconductor–insulator–superconductor to superconductor–insulator–metal–superconductor and superconductor–metal–superconductor type of junctions as the sintering atmosphere is varied from argon to air and oxygen respectively. The scanning electron microscopy in conjunction with energy dispersive spectroscopy studies indicate that the composition fluctuation at the grain boundaries is the reason for such variation