Growth of boron nanostructures with controlled diameter
A process for growth of boron-based nanostructures, such as nanotubes and nanowires, with a controlled diameter and with controlled chemical (such as composition, doping) as well as physical (such as electrical and superconducting) properties is described. The boron nanostructures are grown on a metal-substituted MCM-41 template with pores having a uniform pore diameter of less than approximately 4 nm, and can be doped with a Group Ia or Group IIa electron donor element during or after growth of the nanostructure. Preliminary data based on magnetic susceptibility measurements suggest that Mg-doped boron nanotubes have a superconducting transition temperature on the order of 100 K.
1. A one-dimensional superconducting device comprising a boron nanostructure having a diameter of less than 50 nm and impregnated with an electron donor element, the boron nanostructure having a superconducting transition temperature greater than 36 degrees K, wherein the boron nanostructure comprises a nanotube.
2. The device of claim 1 , wherein the nanotube has a diameter of less than 10 nm.
3. The device of claim 1 , wherein the nanotube is a single-wall nanotube.
4. A one-dimensional superconducting device comprising a boron nanostructure having a diameter of less than 50 nm and impregnated with an electron donor element, the boron nanostructure having a superconducting transition temperature greater than 36 degrees K, wherein the boron nanostructure comprises a nanofiber having a diameter of less than 1 nm.
5. The device of claim 4 , wherein the boron nanostructure comprises a plurality of nanofibers that are aligned in a parallel fashion or intertwined.
6. The device of claim 4 , wherein the nanofiber comprises boron atoms arranged in a polyethylene-like chain structure.
7. A single-wall boron nanotube impregnated with an electron donor element, the nanotube having a diameter less than 100 nm and a superconducting transition temperature greater than 36 degrees K.
8. The nanotube of claim 7 , wherein the electron donor element is selected from an element of Group Ia or Group IIa of the periodic table of elements.
9. The nanotube of claim 7 , wherein the electron donor element is selected from the group consisting of Lithium, Beryllium and Magnesium.
10. The device of claim 7 , wherein the electron donor element comprises magnesium and is incorporated in the boron nanotube with a concentration so as to convert the boron nanostructure into magnesium diboride (MgB 2 ).