Electrical Properties of Li Substituted (Tl0.85Cr0.15)Sr2-x Li x CaCu2O7 Superconductor

The effects of Li substitution for Sr in (Tl0.85Cr0.15)Sr2-x Li x CaCu2O7 (Tl-1212) with x = 0 - 0.10 were investigated. Tl-1212 superconductor pellets were prepared via solid-state reaction and precursor method. The samples were characterized by x-ray diffraction and four-point probe methods. The XRD patterns showed that all samples formed mixed phases of Tl-1212 and Ca0.3Sr0.7CuO2 (CSCO). The temperature-dependent resistance measurements showed metallic-behavior for all samples with onset transition temperature, T c onset between 96 K and 105 K and zero resistance temperature, T c zero between 85 K and 94 K. The transition-width, ΔTc of all samples was in the range of 4 K to 11 K. The x = 0.02 and 0.07 sample showed increase in Tc onset to 105 K and 102 K, respectively. This work showed that Li improved the transition temperature for x = 0.02 and 0.07 samples although the dominant phase was not Tl-1212.