The influence of zinc on Tl-1223 superconductors

The influence of Zn doping on the physical and electrical properties of the Tl-1223 phase has been investigated for samples with the composition (Tl0.5Pb0.5)(Sr0.9Ba0.1)2Ca2(Cu<f>1−x</f>Znx)3O<f>8+δ</f> (<f>x=0</f>, 0.01, 0.05 and 0.1). Sr–Ba–Ca–Cu–Zn containing precursor materials were prepared via malic acid gels followed by a calcination step at 900 °C. Tl2O3 and PbO were added by co-milling. Sintering in oxygen atmosphere yielded high-quality superconducting material. Oxygen annealing, re-grinding and re-sintering improved the electrical properties, leading to critical temperatures (<f>Tc(0)</f>) of 117 K and critical current densities up to 3800 A cm−2 at 77 K for bulk phase material. The addition of Zn increased the content of the Tl-1212 phase, changed the microstructure, decreased the transition temperature slightly and reduced the critical current density at 77 K. [Copyright &y& Elsevier]