The preparation of high transition temperature superconducting Pb-Bi-Ge alloy filaments using the method of glass-coated melt spinning

Abstract

The melt spinning of Pb-Bi-Ge alloys with Pyrex glass was investigated as a means of producing a superconducting long filament with highT _c. Continuous filaments with maximumT _c of more than 10 K of Pb_100-x-y Bi _x Ge _y (15⩽x⩽37 and 7⩽⩽25) were obtained from the molten state at 1500 K with a winding speed of 0.95 m sec⁻¹. The Pb₄₉Bi₃₃Ge₁₈ filament, which was 34×10⁻⁶ m diameter and a ductile material with a tensile strength of 20 MPa and elongation of 2.7%, exhibited superconductivity at the highestT _c of 14.3 K. These filaments were found to be polycrystalline with a grain size of more than 5000×10⁻¹⁰ m and had a mixed structure of germanium (diamond) ε (h c p) and bismuth phases. The germanium element distributed homogeneously in the filament.