Synthesis and processing of bulk (Hg,Pb)Ba2Ca2Cu3Oy (HgPb1223) superconductor using commercial BaCaCuO precursor powders is reported. HgPb1223 is shown to form over a wide range of temperatures, 750-880°C. The micro structure and intergrain connectivity of samples depends strongly on heat treatment and Hg-pressure during synthesis. Use of an external Hg-source during the reaction improves the density of the HgPb1223 products. The chemical nature of the external Hg-source changes the Hg-pressure and influences melting characteristics and grain growth. CaHgO2 is shown to be a particularly effective external Hg-source for producing dense HgPb1223 materials with improved grain growth and texture. Micro structure of HgPb1223 synthesized using CaHgO2 as the external Hg-source is characterized by large colonies of well-aligned superconducting grains. As-synthesized HgPb1223 samples were superconducting with Tc values in the range 132-134 K without post annealing in oxygen or argon. Phase purity and microstructural characteristics are correlated with magnetization measurements.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering