Preparation of biaxially oriented TlCu-1234 thin films

The single phase of TlCu-1234 superconductor thin films is prepared for the first time by the amorphous phase epitaxy (APE) method, which is thallium treatment of sputtered amorphous phase at 900 degrees C for 1 h. The amorph ous phase is prepared by sputtering from the stoichiometric target composit ion CuBa2Ca3Cu4O12-y. The films on the SrTiO3 substrate are aligned biaxial ly after the thallium treatment. Highly reproducible TlCu-1234 films are pr epared by this method. The XRD reflected a predominant single phase with th e c-axis lattice constant of 18.74 Angstrom. This lattice constant value is in between that of Cu-1234 (17.99 Angstrom) and T1-1234 (19.11 degrees). T he pole figure measurements of (103) reflection of the films showed a-axis- oriented crystals with Delta phi = 0.8 degrees. The composition of the film s after Energy Dispersive X-ray (EDX) measurements is Tl0.8Cu0.2Ba2Ca3Cu4O1 2-y. From the resistivity measurements, the T-c is 113 K. Preliminary J(c) measurements showed a current density of 1.0 X 10(6) A/cm(2) (77 K, 0 T). ( C) 1999 Published by Elsevier Science B.V. All rights reserved.