Method for preparing high transition temperature Nb.sub.3 Ge superconductors
AssigneeThe United States of America as represented by the United States Energy Research and Development Administration
InventorsLawrence R. Newkirk, Flavio A. Valencia
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Abstract
Bulk coatings of Nb.sub.3 Ge superconductors having transition temperatures in excess of 20 K are readily formed by a chemical vapor deposition technique involving the coreduction of NbCl.sub.5 and GeCl.sub.4 in the presence of hydrogen. The NbCl.sub.5 vapor may advantageously be formed quantitatively in the temperature range of about 250.degree. to 260.degree. C by the chlorination of Nb metal provided the partial pressure of the product NbCl.sub.5 vapor is maintained at or below about 0.1 atm.
Claims2
In a method of forming bulk coatings of high transition temperature Nb.sub.3 Ge superconductors by the coreduction of flowing Nb and Ge chlorides in the presence of flowing hydrogen, the improvement comprising quantitatively forming NbCl.sub.5 vapor at a desired rate by flowing Cl.sub.2 gas at a desired rate over an excess of Nb metal at a temperature in the range of about 250.degree. to about 260.degree. C, the partial pressure of said NbCl.sub.5 vapor in the presence of said Nb metal being maintained at about 0.1 atm or less, and using said NbCl.sub.5 vapor as the source of the Nb chloride used in said coreduction.
Dependencies are inferred from the claim text.