Superconductivity of Hg (1−x) Ag x Ba 1.9 La 0.1 CuO y (0≤x≤0.6) Materials

Abstract

Hg(1−x)AgxBa1.9La0.1CuOy materials are prepared directly from the oxide powders. Substitution of 5 at.% La3+ for Ba2+ chemically stabilize the materials. Ag substitution for Hg increases the Superconducting volume and enhances the Superconducting grain size. The Lattice parameters of the Superconducting tetragonal phase do not change but Tc decreases with increasing Ag-concentration from 92.5 (x = 0) to 78 K (x = 0.6). Maximum intra-grain critical current density estimated from the magnetization data is 1.4 × 106 A/cm2 (70 K, H = 0) for the composition Hg0.8Ag0.2Ba1.9La0.1CuOy. Ag substitution for Hg transforms the semiconducting HgBa1.9La0.1CuOy to metallic state and the electrical resistivity of the materials decreases with increasing Ag-concentration. Inter-grain critical current density increases with Ag-concentration and a maximum value of 25A/cm2 (77 K; H = 0) is observed. This indicates that the presence of Ag provides extra pinning centers in the grains or at the grain boundaries and enhances the inter-grain electrical conductivity.