Title :
Processing parameters and kinetics of bromination and chlorination in the YBa2Cu3O6+x system
Author :
Radousky, H.B. ; Glass, R.S. ; Back, D. ; Chin, A.H. ; Fluss, M.J. ; Liu, J.Z. ; Mosly, W.D. ; Klavins, P. ; Shelton, R.N.
Author_Institution :
Lawrence Livermore Nat. Lab., CA, USA
fDate :
3/1/1991 12:00:00 AM
Abstract :
The introduction of halogens such as Cl2 and Br2 can restore 90 K superconductivity to oxygen deficient YBa2 Cu3O6+x. This is potentially important for applications to thin-film devices due to the low processing temperatures required relative to reprocessing with oxygen. Low-temperature (260°C) and short-time (>5 min) bromination has been shown to convert initially insulating YBa2Cu3O6.2 powder to a high-temperature superconductor with properties similar to the standard O7 material. This process has now been extended to single crystals as well, but with somewhat different processing parameters. Thermal gravimetric analysis (TGA) coupled with mass spectrometry indicated that the Br becomes strongly bonded with no release of Br observed in taking powder samples to 1000°C in flowing forming gas (2%H2/98%N2). The reaction has also been found to be highly exothermic for both Br and Cl treatments, which is consistent with the strong bonding of the bromine
Keywords :
barium compounds; high-temperature superconductors; mass spectroscopic chemical analysis; materials preparation; reaction kinetics; superconducting junction devices; superconducting thin films; thermal analysis; yttrium compounds; 260 degC; 90 K; TGA; YBa2Cu3O6+x; bromination; chlorination; flowing forming gas; high-temperature superconductor; kinetics; mass spectrometry; powder samples; processing temperatures; strong bonding; thin-film devices; Bonding; Crystalline materials; High temperature superconductors; Insulation; Kinetic theory; Powders; Superconducting materials; Superconducting thin films; Superconductivity; Thin film devices;
Journal_Title :
Magnetics, IEEE Transactions on
