Synthesis of thallium-1223 high-temperature superconducting phase by sol-gel method

Author: Amiran Tchankvetadze
Keywords: superconductivity, precursor, sol-gel method, carbonate
Annotation:

The high-temperature superconductors Tl-1223 show a superconducting transition temperature Tc above 118 K, and when synthesized under high pressure, the critical temperature can reach 133.5 K. The unit of the formula and the crystal structure of the TlBa2Can-1CunO2n+2+δ system are similar to the formulas for the HgBa2Can-1CunO2n+2+δ system, where n is the number of adjacent Cu-O layers. What is very important is that both systems critically depend on the properties of the precursor to achieve a high-purity superconductivity phase. The volatility of the thallium oxide at high temperatures is one of the problems in its practical application. Respectively, it is not possible to apply these superconductive materials. Despite this, the high critical transition temperature in the superconductivity state makes the Tl-1223 phase a winsome material for its practical utilization, and intense research activity has not decreased until the present day. The present study is devoted to synthesizing Tl-1223 high-temperature superconductors by the sol-gel method. We must note that oxides and carbonate-containing compounds are used as starting materials, and PVA/PVAc was used as the complexing agent in a sol-gel route. Studies have shown that the precursor synthesized under flowing oxygen at 915oC has a high reactivity condition. As a result, we obtained a pure Tl-1223 phase with good physical and chemical properties.