Fluorinated precursors of superconducting ceramics, and methods of making the same
This invention provides a method of making a fluorinated precursor of a superconducting ceramic. The method comprises providing a solution comprising a rare earth salt, an alkaline earth metal salt and a copper salt; spraying the solution onto a substrate to provide a film-covered substrate; and heating the film-covered substrate in an atmosphere containing fluorinated gas to provide the fluorinated precursor.
1. A method of increasing the quality of a precursor film, the method comprising:
heat treating said precursor film at atmospheric or sub-atmospheric pressure in the presence of fluorinated gas and oxygen to produce a resultant precursor film; and
heating said resultant precursor film in an atmosphere comprising water vapor and oxygen at atmospheric or sub-atmospheric pressure to produce a crystalline film.
2. A method according to claim 1 wherein said atmosphere further comprises nitrogen.
3. A method according to claim 1 wherein heat treating said precursor film comprises heating a precursor film to a temperature of about 400° C. to about 800° C. for about a half an hour to about three hours at about 1 to 760 Torr.
4. A method of inhibiting the conversion of a fluorinated precursor film into a crystalline film, wherein the fluorinated precursor film comprises rare earth metal, alkaline earth metal cuprate, said method comprising adding a small amount of fluorinated gas during a heat treatment process by which a fluorinated precursor film is to be converted into a crystalline film.
5. A method according to claim 4 wherein the fluorinated gas is added at a pressure of approximately 10 milliTorr or greater during said heat treatment process.