Title :
Advances in HTS films for high power microwave applications
Author :
Face, D.W. ; Wilker, C. ; Kingston, J.J. ; Zhi-Yuan Shen ; Pellicone, F.M. ; Small, R.J. ; McKenna, S.P. ; Shiquan Sun ; Martin, P.J.
Author_Institution :
DuPont Superconductivity, Wilmington, DE, USA
fDate :
6/1/1997 12:00:00 AM
Abstract :
This paper describes recent work at DuPont to extend the high power microwave performance of YBa/sub 2/Cu/sub 3/O/sub 7/ and Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ high-T/sub c/ superconducting (HTS) films. The YBa/sub 2/Cu/sub 3/O/sub 7/ films grown by in-situ off-axis magnetron sputtering using are produced by in-situ off-axis sputtering with radiant substrate heating. The Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ films are produced by off-axis sputtering followed by annealing in oxygen and Tl/sub 2/O vapor. The microwave surface resistance and power handling of these films has been measured over a wide range of temperature (20 K to 100 K) using a HTS-sapphire resonator technique. At 70 K, the surface resistance of YBa/sub 2/Cu/sub 3/O/sub 7/ films remains below 65 /spl mu//spl Omega/ (@5.56 GHz) with microwave surface current densities up to 5/spl times/10/sup 6/ A/cm/sup 2/. At 70 K, the surface resistance of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ films remains below 200 /spl mu//spl Omega/ (@8.1 GHz) with microwave current densities up to 2/spl times/10/sup 6/ A/cm/sup 2/.
Keywords :
annealing; barium compounds; calcium compounds; critical current density (superconductivity); high field effects; high-temperature superconductors; sputtered coatings; superconducting microwave devices; superconducting thin films; surface conductivity; thallium compounds; yttrium compounds; 20 to 100 K; HTS films; Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/; YBa/sub 2/Cu/sub 3/O/sub 7/; annealing; high power microwave applications; magnetron sputtering; microwave current density; microwave surface resistance; power handling; radiant substrate heating; Annealing; Current density; Electromagnetic heating; High temperature superconductors; Microwave theory and techniques; Sputtering; Superconducting films; Superconducting magnets; Superconducting microwave devices; Surface resistance;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
