Normal pressure synthesis of Cu1-xTlxBa2Ca2Cu3O10-δ superconductor

A very simple method for the direct synthesis of Cu0.5Tl0.5Ba2Ca2Cu3O10-y superconductor is discovered. A predominant single phase of Cu0.5Tl0.5Ba2Ca2Cu3O10-y is achieved by the solid state reaction of Ba(NO3)(2), CaCO3 and Cu(CN) at 840degreesC. The material after firing in air was ground and mixed with Tl2O3 in appropriate ratios and palletized. Pellets were wrapped in aluminum foil and were heat treated at 840degreesC for 5-30 min. Predominant single phase of Cu0.5Tl0.5Ba2Ca2Cu3O10-delta was achieved with a very small amount of impurity phase. The onset T-c of the material is 110 K and T-c(R = 0) = 103 K. The critical temperature is confirmed by resistivity and magnetic susceptibility measurements. The composition of the material was measured by EDX technique. The as-prepared material was found to be in the carrier over-doped region and after post-annealing in air/N-2, material was promoted to the region of carrier optimum doping. The zero resistivity critical temperature of the material was increased to 103 K with the post-annealing in air/N-2 atmosphere. FTIR absorption measurement manifested the formation of optimum doped material after postannealing, (C) 2004 Elsevier B.V. All rights reserved.