Nove Technologies Develops Nanoparticle Magnesium Diboride Superconductors

Nove Technologies, Inc. (Metamora, MI) inventor Matthew J. Holcomb created a superconductor comprising particles and nanoparticles made of a superconductive material, and a conductive material.  The superconductor particles preferably have sizes generally within the range of 1.5 nanometers to 10 microns in diameter. The conductive material is selected to be driven to a superconductive state when in proximity to the superconductive material, and preferably at least includes bismuth. An unbroken length of the conductive material is located sufficiently close to a plurality of the particles to be driven to a superconductive state by the superconductive material, according to U.S. Patent 7,745,376.

The Nove Technologies invention provides a superconductor composite material comprising particles made of a superconductive material, and a conductive material. The conductive material is selected to be driven to a superconductive state when in proximity to the superconductive material, and preferably at least includes bismuth. An unbroken length of the conductive material is located sufficiently close to a plurality of the particles to be driven to a superconductive state by the superconductive material.

The superconductive material may be a planar diboride. The planar diboride is preferably magnesium diboride. 

U.S. Patent 7,745,376, FIG. 46 shows scanning electron microscope images of the several embodiments of mono-filamentary SMMC powder-in-tube wire. The images shows the microstructure of the magnesium diboride/metal composites as well, with the light areas identified at the metal matrix and the dark areas as the MgB2 particles. All wires shown are encased in a copper sheath.

The invention also provides a method of making such a superconductor. The invention also provides a method of making a wire of such a superconductor. An elongate member may be assembled from the particles and the conductive material, and be drawn into a wire.

Nove Technologies’ superconductor/metal matrix composite (SMMC) may use bismuth or a bismuth-based alloy as a ductile matrix metal which is driven to superconductivity by the proximity effect.

High current density SMMC wires and tapes can be fabricated using metal matrix materials that are chemically compatible with the superconductor particles and that possess a high lambda. In general, the higher the .lamda., the higher the current-carrying capacity of the final composite. 

The discovery of high critical temperature (Tc) superconducting ceramics (HTS ceramics) has inspired an enormous interest in their application. Conventional niobium alloy superconductors such as NbTi must be cooled to below 10K to achieve useful superconductivity. HTS superconductors, on the other hand, can have Tcs over 100K. Due to the great expense of cryogenic refrigeration, the HTS ceramics could find much wider application in industrial and laboratory devices. Of particular interest are materials which have Tc above 77K, because this is the temperature of liquid nitrogen, a common and relatively inexpensive refrigerant.

HTS ceramics have not been used in many potential applications because they suffer from a number of shortcomings. The most severe problems with the HTS ceramics are as follows: 1) HTS ceramics are brittle. They are not flexible and thus cannot readily be made into wires or other useful shapes. Cracks and boundaries between adjacent crystals severely limit supercurrent flow. 2) HTS ceramics are highly anisotropic. Supercurrents preferentially flow in certain directions with respect to the crystal lattice, reducing the maximum current density in randomly oriented multicrystalline pieces. 3) HTS ceramics are strong oxidizing agents. Most metals, such as copper, lead, tin, aluminum, indium, and niobium, are oxidized by contact with the ceramic superconductors. Insulating oxide layers impede supercurrent flow. Only noble metals such as gold, silver palladium and their alloys are not oxidized by the HTS ceramics.