Possibilities Of T-C Enhancement For Already Known Htsc Compounds

Enhancement of T-c was attempted for RE 123 and Bi(Pb)2223 superconductors, because these materials have been well-developed for practical applications, while their T-c's are lower compared to other compounds having similar microstructures, such as Hg1212 and T12223, respectively. For the RE123 system, many factors, such as selection of RE element, partial RE substitution for Ba and incorporation of impurities including C, affect T-c mainly through the change of local crystal structure, however, effective methods for large enhancement of T-c were not found. On the other hand, T-c of Bi(Pb)2223 was successfully enhanced up to 116 K by post-annealing at similar to 700 degrees C for a long time. Change in cation composition during annealing was suggested to contribute the T-c enhancement of Bi(Pb)2223. (c) 2007 Published by Elsevier B.V.