EFFECTS OF MILLING AND AG DOPING ON THE FABRICATION OF LABA2CU3OY SUPERCONDUCTOR

The effects of milling and Ag addition on the decomposition of single- phase LaBa2Cu3Oy have been evaluated. It was found that the decomposit ion of milled single-phase LaBa2Cu3Oy powders when sintered in pure N2 is attributed to the introduction of strain in the lattice which caus es the instability of the structure. The possible reasons why single-p hase LaBa2Cu3Oy could be synthesized by sintering in pure N2 at high t emperatures and its transition width is always broadened are proposed. The decomposition of compacts of unmilled powders of single-phase LaB a2Cu3Oy when sintered in pure N2 for a long time is due to the fact th at oxygen diffuses along the grain boundaries and evolves through the surface of the specimens. Silver might segregate to the grain boundari es and prevent decomposition. It is suggested that to obtain a high-qu ality LaBa2Cu3Oy, sintering in the reduced atmosphere to achieve a pro per oxygen content is required. Reduced atmosphere and Ag addition cou ld enhance the densification rate. For Ag-doped specimens, T(c) is hig hest for x = 0.0001, but decreases for x > 0.0001.