PREPARATION OF TLBA2CA2CU3O9-PLUS-OR-MINUS-DELTA HIGH T(C)THIN FILMS BY LASER-ABLATION IN COMBINATION WITH THERMAL EVAPORATION OF THALLIUM OXIDE

TlBa2Ca2Cu3O9+/-delta high T(c) thin films were prepared on MgO [100] surfaces by a combination of laser ablation from a stoichiometric Ba2C a2Cu3Ox target and the thermal evaporation of thallium oxide. X-ray di ffraction measurements showed that the films consisted of predominantl y c axis oriented TlBa2Ca2Cu3O9+/-delta, and scanning electron microsc opy revealed that the surfaces had a flat, platelike morphology. The a c inductive measurements indicated that the onset of superconductivity occurred at 117 K with a transition width (10%-90%) of approximately 3 K. Zero resistivity was reached at 120 K. The critical current densi ty was approximately 3 X 10(4) A/cm2 at 110 K.