Epitaxial superconducting Tl0.5Pb0.5Sr1.6Ba0.4Ca2Cu3O9 films on LaAlO3 by thermal spray and post-spray annealing

A simple, low-cost and easily scalable method-thermal spray followed by post-spray annealing-has been successfully demonstrated for fabricating high-J(c) epitaxial superconducting films of TI0.5Pb0.5Sr1.6Ba0.4Ca2CU3O9 [(Tl, Pb)-1223]. The process was performed by spraying a stoichiometric solution containing Tl, Pb, Sr, Pa, Ca and Cu nitrates onto LaAlO3 substrates heated to 300-400 degrees C. Subsequently, the amorphous films were placed inside a silver containment along with two semicircular unfired pellets, and were reacted and crystallized by a thermal anneal at 870 degrees C in air. X-ray diffraction showed that the films consist mainly of c-axis aligned (Tl, Pb)-1223 phase with a small amount of (Tl, Pb)-1212 phase. X-ray phi-scans revealed very good epitaxial growth. Four-probe transport measurements on a 4 mm wide and 1.2 mu m thick film Showed a superconducting transition temperature of 106-109 K, with a zero-field critical current of 51 A at 77 K, which corresponds to a critical current density of 1.1 x 10(6) A cm(-2).