Superconducting wires and methods of making thereof
View Patent ↗Disclosed herein are superconducting wires. The superconducting wires can comprise a metallic matrix and at least one continuous subelement embedded in the matrix. Each subelement can comprise a non-superconducting core, a superconducting layer coaxially disposed around the non-superconducting core, and a barrier layer coaxially disposed around the superconducting layer. The superconducting layer can comprise a plurality of Nb 3 Sn grains stabilized by metal oxide particulates disposed therein. The Nb 3 Sn grains can have an average grain size of from 5 nm to 90 nm (for example, from 15 nm to 30 nm). The superconducting wire can have a high-field critical current density (J c ) of at least 5,000 A/mm 2 at a temperature of 4.2 K in a magnetic field of 12 T. Also described are superconducting wire precursors that can be heat treated to prepare superconducting wires, as well as methods of making superconducting wires.
1. A superconducting wire comprising:
a matrix comprising a Cu-based metal; and
at least one continuous subelement embedded in the matrix;
wherein each subelement comprises:
a non-superconducting core;
a superconducting layer coaxially disposed around the non-superconducting core; and
a barrier layer coaxially disposed around the superconducting layer;
wherein the superconducting layer comprises a plurality of Nb 3 Sn grains stabilized by metal oxide particulates disposed therein,
wherein the Nb 3 Sn grains have an average grain size of from 5 nm to 90 nm; and
wherein the superconducting layer has a flux pinning force vs. field (F p -B) curve that peaks at from 0.2 to 0.5 times the irreversibility field (B irr ).
2. The superconducting wire of claim 1 , wherein the Nb 3 Sn grains have an average grain size of from 15 nm to 50 nm.
3. The superconducting wire of claim 1 , wherein the superconducting layer further comprises a dopant.
4. The superconducting wire of claim 3 , wherein the dopant comprises Ti, Ta, or a combination thereof.
5. The superconducting wire of claim 1 , wherein the superconducting layer has a high-field critical current density (J c ) of from 5,000 to 21,000 A/mm 2 at a temperature of 4.2 K in a magnetic field of 12 T.
6. The superconducting wire of claim 1 , wherein the barrier layer comprises a Nb alloy, a Ta alloy, a Ti alloy, or a combination thereof.
7. The superconducting wire of claim 6 , wherein the barrier layer comprises a Nb alloy, and the Nb alloy comprises an alloy of Nb and a metal that has an oxidation potential greater than the oxidation potential of Nb.
8. The superconducting wire of claim 1 , wherein the superconducting layer comprises a Nb alloy, and the Nb alloy is selected from the group consisting of a Nb—Zr alloy, a Nb—Al alloy, a Nb—Ti alloy, and combinations thereof.
9. The superconducting wire of claim 1 , wherein the metal oxide particulates comprise a metal that has an oxidation potential greater than the oxidation potential of Nb.
10. The superconducting wire of claim 1 , wherein the metal oxide particulates comprise a metal oxide selected from the group consisting of ZrO 2 , Al 2 O 3 , TiO 2 , and combinations thereof.
11. The superconducting wire of claim 1 , wherein the diameter of each subelement is from 5 μm to 150 μm.
12. The superconducting wire of claim 1 , wherein the metal oxide particulates comprise a metal selected from the group consisting of Sn, Cu, Zn, Nb, Fe, Ni, Cr, Co, W, and combinations thereof.
13. The superconducting wire of claim 1 , wherein the non-superconducting core comprises Sn metal or an alloy thereof.