Transport Critical Current Densities in Uniaxially and Biaxially Oriented Tl₁(Ba_0.8Sr_0.2)₂Ca₂Cu₃O₉Superconducting Films on Ag and SrTiO₃Substrates Prepared by a Spray Pyrolysis Method

Abstract

Tl 1 (Ba 0.8 Sr 0.2 ) 2 Ca 2 Cu 3 O 9 films were prepared by a spray pyrolysis method on SrTiO 3 (100) single crystal substrates and on polycrystalline Ag tapes. The biaxially ( c - and a -axes) oriented Tl 1 (Ba 0.8 Sr 0.2 ) 2 Ca 2 Cu 3 O 9 film on SrTiO 3 single crystal substrate showed very high performance of the transport J c , i.e. 2.8×10 5 A/cm 2 at 77 K, 0 T and 5.0×10 4 A/cm 2 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 8.0×10 4 A/cm 2 , at 77 K, 0 T, and of 6.9×10 3 A/cm 2 , at 77 K, 1 T ( H // c - axis). In the c -axis oriented Tl 1 (Ba 0.8 Sr 0.2 ) 2 Ca 2 Cu 3 O 9 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.