OPTIMIZATION OF SYNTHETIC PARAMETERS FOR TL-2201 SUPERCONDUCTING PHASE BY FLASH SINTERING PROCESS

Samples with nominal composition T12Ba2Cu1.2 (copper-rich Tl-2201 ) we re calcined at various temperature, i.e. from 865-degrees-C to 910-deg rees-C and for various durations ( 10-20 h). The samples were sintered for 32 1/2 min at various temperatures. The X-ray powder diffraction pattern indicates that most of the TI-Ba-Cu samples (Tl-2201 ) are sin gle-phase materials. All the lines in the X-ray pattern are indexible on a tetragonal unit cell showing tetragonal symmetry having space gro up 14/mmm with a = 3.86 angstrom, c = 23.11 +/- 0.06 angstrom as unit cell parameters. R-T and AC susceptibility measurements show T(c)on, f rom 90 to 104 K. There is an elongation of the c-axis (c = 23.24 angst rom) for the sample showing the highest T(c). Wet chemical analysis co nfirms the deficiency of thallium. This suggests some substitution of Cu in place of thallium which leads to an increase in the average oxid ation state of copper, responsible for the creation of holes (charge c arriers).