Effect of Starting Materials and Heat Treatments on T1-Based High-Tc Superconductors
Superconducting samples of the same nominal composition of TlCaBaCuO4.5±× have been prepared by the aid of different starting materials and heat treatments. They have the critical temperatures of 0 K (no zero resistivity), 106 K, 111 K, 121 K, 92 K and 105 K respectively. It has been stated the highest Tc belongs to the most crystallized and essentially single-phase structure. In the most cases the phase of Tl2CaBa2Cu2O8 is responsible for the superconductivity. Certain content of the T12Ca2Ba2Cu3OlO phase and some unidentified phases can also be found. A time-dependent character of some samples has been observed too.
KeywordsHeat Treatment Critical Temperature Contact Resistance Nominal Composition Heat Treatment Process
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