Title :
Reactive nanophase oxide additions to melt-processed high-T/sub c/ superconductors
Author :
Goretta, K.C. ; Brandel, B.P. ; Lanagan, M.T. ; Hu, J.G. ; Miller, D.J. ; Sengupta, S. ; Parker, J.C. ; Ali, M.N. ; Nan Chen
Author_Institution :
Argonne Nat. Lab., IL, USA
fDate :
6/1/1995 12:00:00 AM
Abstract :
Nanophase TiO/sub 2/ and Al/sub 2/O/sub 3/ powders were synthesized by a vapor-phase process and mechanically mixed with stoichiometric YBa/sub 2/Cu/sub 3/O/sub x/ and TlBa/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ powders in 20 mole% concentrations. Pellets produced from powders with and without nanophase oxides were heated in air or O/sub 2/ above the peritectic melt temperature and then slowly cooled. At 4.2 K, the intragranular critical current density (J/sub c/) increased dramatically with the oxide additions. At 35-50 K, effects of the oxide additions were positive, but less pronounced. At 77 K, the additions decreased J/sub c/, probably because they depressed the transition temperature.<>
Keywords :
alumina; barium compounds; calcium compounds; critical current density (superconductivity); flux pinning; high-temperature superconductors; powder technology; superconducting transition temperature; thallium compounds; titanium compounds; yttrium compounds; 35 to 50 K; 4.2 K; Al/sub 2/O/sub 3/; Al/sub 2/O/sub 3/ powders; TiO/sub 2/; TiO/sub 2/ powders; TlBa/sub 2/Ca/sub 2/Cu/sub 3/O; TlBa/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ powders; YBa/sub 2/Cu/sub 3/O; flux pinning; intragranular critical current density; mechanically mixed; melt-processed high-T/sub c/ superconductors; peritectic melt temperature; reactive nanophase oxide additions; stoichiometric YBa/sub 2/Cu/sub 3/O/sub x/; transition temperature; vapor-phase process; Costs; Critical current density; Flux pinning; High temperature superconductors; Laboratories; Powders; Superconducting transition temperature; Superconductivity; Temperature distribution; US Department of Energy;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
