SYNTHESIS OF TL-BASED 2234 SUPERCONDUCTORS

Nearly single-phase samples of superconducting Tl-Ba-Ca-Cu-O "2234" were successfully synthesized. The sample sintered in air had T(c) of 112 K. Post-annealing of the sintered sample in a high-pressure oxygen gas made its T(c) increase up to 115 K. The sample sintered in argon gas had T(c) of 90 K. The thermoelectric power (TEP) of the sample was also measured. All the samples showed positive TEP signals. The magnitude of TEP signal decreased as T(c) increased. Thus, it was likely that the as-sintered 2234 phase was in an under-doped state with respect to the optimum carrier concentration.