Improvement of the Irreversibility Line of the 1212 Compound Tl 0.5 Pb 0.5 Sr 2 CaCu 2 O 7−δ

Abstract

The superconducting properties and the irreversibility line of the Tl0.5Pb0.5Sr2CaCu2O7−δ were studied by ac susceptibility on both ceramic and powder samples prepared in sealed quartz tube at 960°C. In parallel, carefull investigations by DTA/Tg, X rays diffraction and plasma emission spectroscopy were performed on each sample after each thermal treatment. It is shown that the superconducting properties are strongly dependent on further heat treatments and that the irreversibility line may be optimized. Nevertheless, the results obtained suggest that further improvement of the irreversibility line might be expected.