Normal pressure synthesis of Cu 1− xTl xBa 2Ca 2Cu 3O 10− δ superconductor

Abstract

A very simple method for the direct synthesis of Cu 0.5Tl 0.5Ba 2Ca 2Cu 3O 10− y superconductor is discovered. A predominant single phase of Cu 0.5Tl 0.5Ba 2Ca 2Cu 3O 10− y is achieved by the solid state reaction of Ba(NO 3) 2, CaCO 3 and Cu(CN) at 840 °C. The material after firing in air was ground and mixed with Tl 2O 3 in appropriate ratios and palletized. Pellets were wrapped in aluminum foil and were heat treated at 840 °C for 5–30 min. Predominant single phase of Cu 0.5Tl 0.5Ba 2Ca 2Cu 3O 10− δ 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 post-annealing.