Abstract: This invention pertains to a void-free superconducting magnesium diboride (MgB2) product, especially wire, and to a method for its fabrication. The product is a well-connected and void-free superconducting magnesium diboride. The fabrication method includes the steps of: 1) charging a metal billet or tube with magnesium and boron, or magnesium diboride; 2) sealing the billet; 3) heating the filled and sealed billet to an elevated temperature above room temperature at which the billet metal can be hot-worked and at which reaction between magnesium and boron to form magnesium diboride proceeds or magnesium diboride can be deformed; and 4) hot-rolling the billet until the desired magnesium diboride dimensions and the reaction are achieved. There is an optional step of hot-treating the billet after hot-rolling to change superconducting properties of magnesium diboride by modifying microstructure thereof.

Abstract: Hg,Tl-based superconductors are produced by HIPping. A new superconducting phase, having a double (Hg,Tl)-layer and the nominal composition:(Hg.sub.1-x Tl.sub.x).sub.2 (Ba.sub.1-a Sr.sub.a).sub.2 (Ca.sub.1-b Y.sub.b).sub.2 Cu.sub.3 O.sub.zwhere 0.ltoreq.x.ltoreq.0.95, 0.ltoreq.a.ltoreq.1, 0.ltoreq.b.ltoreq.1, and z is sufficient to provide said phase with a resistive and magnetic superconducting transition of 100 K or above, can be produced. Either precursor oxides, or partially or fully reacted mixed oxides, can be used in the HIPping mixture.

Abstract: The order parameter of a superconductor is reduced by injecting spin-polarized carriers into the superconductor. The reduction in the order parameter is used to modulate the critical current of the superconductor. In a typical embodiment, a current is caused to flow through a superconductor. Spin polarized electrons are then injected into the path of the current in the superconductor by biasing a magnetic metal with respect to a terminal of the superconductor. The bias current may be varied to modulate the injection and thus the flow of current through the superconductor.

Abstract: Hg,Tl-based superconductors are produced by HIPping. A new superconducting phase, having a double (Hg,Tl)-layer and the nominal composition:(Hg.sub.1-x Tl.sub.x).sub.2 (Ba.sub.1-a Sr.sub.a).sub.2 (Ca.sub.1-b Y.sub.b).sub.2 Cu.sub.3 O.sub.zwhere 0.ltoreq.x.ltoreq.0.95, 0.ltoreq.a.ltoreq.1, 0.ltoreq.b.ltoreq.1, and z is sufficient to provide said phase with a resistive and magnetic superconducting transition of 100K or above, can be produced. Either precursor oxides, or partially or fully reacted mixed oxides, can be used in the HIPping mixture.