SG and SSR approach in the preparation of precursors and influence on superconducting properties of Tl-1223 superconductors

Abstract

Abstract The paper presents the comparative analysis of the Sol-gel (SG) and solid-state reaction (SSR) route for the synthesis of precursors for thallium-based superconductors. Samples were prepared a two-step method and by sealed quartz tube technique in ambient pressure. Heat treatments of precursors showed that to obtain high-purity precursors, without any carbonate contamination for SG methods is sufficient to heat treatments at 915oC temperatures and for SSR methods 945oC. The diamagnetic onset temperature of the superconducting transition for the TlBa2Ca2Cu3O8+δ samples prepared by precursors SG at 915oC and SSR at 945oC is about T = 120 K and full screening of applied ac magnetic fields observed at T ≈ 102 K and T ≈ 94 K, respectively. The value of Jc transport critical current densities for SSR obtained 128 A/cm2, whereas for the SG sample and exactly 174 A/cm2. We could conclude that the, using the wet chemistry offers some advantages in comparison with the classical solid-state ceramics processing, especially, better chemical homogeneity and higher reactivity of the precursor powder.