Superconductivity in Dense MgB₂ Wires

الأصل · EN

MgB₂ becomes superconducting just below 40 K. Whereas porous polycrystalline samples of MgB₂ can be synthesized from boron powders, in this letter we demonstrate that dense wires of MgB₂ can be prepared by exposing boron filaments to Mg vapor. The resulting wires have a diameter of 160 μm, are better than 80% dense and manifest the full χ= -1/4π shielding in the superconducting state. Temperature-dependent resistivity measurements indicate that MgB₂ is a highly conducting metal in the normal state with ρ(40 K) = 0.38 μOhm-cm. Using this value, an electronic mean free path, l ≈ 600 Å can be estimated, indicating that MgB₂ wires are well within the clean limit. Tc, Hc₂(T), and Jc data indicate that MgB₂ manifests comparable or better superconducting properties in dense wire form than it manifests as a sintered pellet.