Title :
GdBa/sub 2/Cu/sub 3/O/sub x/ for microwave applications: preparation, properties and devices
Author :
Jedamzik, D. ; Trowles, T.P. ; Zammattio, S.J. ; Stephan, R.E. ; Lamacraft, K. ; Phillips, W.A. ; Hedges, S.J. ; Adams, M. ; Nicholson, B.F.
Author_Institution :
GEC Marconi Ltd., Wembley, UK
fDate :
3/1/1993 12:00:00 AM
Abstract :
GdBa/sub 2/Cu/sub 3/O/sub 7/, which has very similar properties to YBa/sub 2/Cu/sub 3/O/sub 7/ but appears to be more tolerant of processing conditions, is studied. Thin films have been prepared by inverted cylindrical magnetron sputtering on MgO single crystals and routinely give transition temperatures above 92 K and critical currents above 10/sup 6/ A/cm/sup -2/ at 77 K. Films with areas exceeding 12 cm/sup 2/ have been fabricated on 0.5-mm-thick substrates. Structural and compositional studies show a high degree of film perfection. Measurements of surface resistance, using a cavity endwall replacement technique at 60 GHz, give values <20 m Omega at 77 K (uncorrected for film thickness. typically 0.4-0.5 mu m) and suspended substrate stripline resonators give Q values over an order of magnitude larger than the corresponding gold resonator. A 2% 4-GHz filter has been realized in microstrip with a minimum insertion loss below 0.6 dB.<>
Keywords :
Q-factor; X-ray fluorescence analysis; band-pass filters; barium compounds; critical current density (superconductivity); electron probe analysis; gadolinium compounds; high-temperature superconductors; microwave filters; microwave measurement; sputter deposition; superconducting microwave devices; superconducting thin films; superconducting transition temperature; surface conductivity; 0.4 to 0.5 micron; 0.5 mm; 4 GHz; 60 GHz; 77 K; GdBa/sub 2/Cu/sub 3/O/sub 7/; MgO single crystal; X-ray fluorescence; band pass filter; cavity endwall replacement technique; critical currents; electron probe microanalysis; filter; inverted cylindrical magnetron sputtering; microstrip; microwave measurement; quality factor; surface resistance; suspended substrate stripline resonators; transition temperatures; Critical current; Crystals; Electrical resistance measurement; Q measurement; Sputtering; Stripline; Substrates; Surface resistance; Temperature; Thickness measurement;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
