Title :
Surface resistance of bulk and thick film YBa2Cu3 Ox/ss
Author :
Alford, N. McN ; Button, T.W. ; Peterson, G.E. ; Smith, P.A. ; Davis, L.E. ; Penn, S.J. ; Lancaster, M.J. ; Wu, Z. ; Gallop, J.C.
Author_Institution :
ICI Adv. Mater., Runcorn, UK
fDate :
3/1/1991 12:00:00 AM
Abstract :
The surface resistance Rs of YBa2Cu3 O7 (YBCO) has been measured by means of a coaxial method using a copper outer shield and an HTS (high-temperature superconductor) central conductor as well as by means of an all-YBCO TE 011, cavity. The microstructure of the ceramic deliberately altered so that variables such as starting powder size and phase purity, ceramic density, phase composition, grain size, and number of grain boundaries can be evaluated. A number of experiments have been conducted so that the variables chosen might be studied independently. The results show that Rs varies in a complex manner according to the microstructure and that as sintered grain size is reduced to a certain size the Rs is reduced. Further decreases in grain size are associated with an increase in the number of grain boundaries and an increase in the Rs, suggesting that grain boundary detritus and grain boundaries themselves are sources of loss. The Rs is also highly dependent oil crystallographic orientation, and examples are given to show that Rs diminishes in c-axis-oriented YBCO thick films
Keywords :
barium compounds; high-temperature superconductors; surface conductivity; thick films; yttrium compounds; ceramic; ceramic density; grain boundaries; grain size; high temperature superconductor; microstructure; phase composition; phase purity; starting powder size; surface resistance; thick film YBa2Cu3Ox/ss; Ceramics; Coaxial components; Electrical resistance measurement; Grain boundaries; Grain size; High temperature superconductors; Microstructure; Surface resistance; Thick films; Yttrium barium copper oxide;
Journal_Title :
Magnetics, IEEE Transactions on
