Transport Critical Current Densities in Uniaxially and Biaxially Oriented Tl1(Ba0.8Sr0.2)2Ca2Cu3O9 Superconducting Films on Ag and SrTiO3 Substrates Prepared by a Spray Pyrolysis Method

Abstract

Tl1(Ba0.8Sr0.2)2Ca2Cu3O9 films were prepared by a spray pyrolysis method on SrTiO3(100) single crystal substrates and on polycrystalline Ag tapes. The biaxially ( c- and a-axes) oriented Tl1(Ba0.8Sr0.2)2Ca2Cu3O9 film on SrTiO3 single crystal substrate showed very high performance of the transport J c, i.e. 2.8×105 A/cm2 at 77 K, 0 T and 5.0×104 A/cm2 at 77 K, 1 T (H//c- axis). In contrast, the c-axis oriented film was obtained on Ag tape with the J c of 8.0×104 A/cm2, at 77 K, 0 T, and of 6.9×103 A/cm2, at 77 K, 1 T (H//c- axis). In the c-axis oriented Tl1(Ba0.8Sr0.2)2Ca2Cu3O9 film, the weak link behavior remained, however the weak magnetic field dependence of the J c and the very high J c in the biaxially oriented film suggested that the weak link problem was eliminated. We concluded it would be necessary to get the biaxial orientation to produce practical wires of Tl-1223.