The preparation of an enhanced-T<sub>c</sub> superconducting Tl<sub>2</sub>Ba<sub>2</sub>CuO<sub>x</sub> phase by using low Tl concentrations
K K Saini; C P Sharma; S N Ekbote; D K Suri; P Asthana; Chanderkant; K C Nagpal; S A Agnihotry; S Chandra; K K Saini; Nat. Phys. Lab., New Delhi, India; C P Sharma; Nat. Phys. Lab., New Delhi, India; S N Ekbote; Nat. Phys. Lab., New Delhi, India; D K Suri; Nat. Phys. Lab., New Delhi, India; P Asthana; Nat. Phys. Lab., New Delhi, India; Chanderkant; Nat. Phys. Lab., New Delhi, India; K C Nagpal; Nat. Phys. Lab., New Delhi, India; S A Agnihotry; Nat. Phys. Lab., New Delhi, India; S Chandra; Nat. Phys. Lab., New Delhi, India
Журнал:
Journal of Physics: Condensed Matter
Дата:
1990-07-09
Аннотация:
Calcium-free high-T<sub>c</sub> superconducting compounds of the Tl<sub>2</sub>Ba<sub>2</sub>Ca<sub>n-1</sub>Cu<sub>n</sub>O<sub>x</sub> series have been fabricated with an enhanced onset critical temperature, T<sub>c</sub><sup>on</sup> approximately=97.2 K. The optimisation of parameters has revealed that the choice of nominal composition plays an important role in the formation of the final phase. While a nominal 2201 composition did not yield a high-T<sub>c</sub> phase, compounds with low thallium concentration (1201) gave a 2201 high-T<sub>c</sub> phase. XRD studies confirm the formation of a 2201 phase from 1201 and <sup>1</sup>/<sub>2</sub>201 phases with a approximately=3.86 AA and c approximately=23.23 AA. It has also been found that a high sintering temperature of 97 degrees C maintained for a short duration of three to five minutes is favourable for the enhancement of T<sub>c</sub>.
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