REPRODUCIBLE SYNTHESIS BY METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION ANDTHALLIUM VAPOR DIFFUSION OF ORIENTED THIN-FILMS TL1- INTERGROWTH OF TLBA2CA2CU3O9 AND TL2BA2CA2CU3O10 STRUCTURES(XBA2CA2CU3O9+X )

Superconducting thin-films containing randomly disordered layers of Tl Ba2Ca2Cu3O9 and Tl2Ba2Ca2Cu3O10 have been synthesized through a combin ed approach of metal-organic chemical vapour deposition (MOCVD) and th allium vapour diffusion. The BaCaCu matrices have been deposited onto yttria stabilized zirconia (YSZ) substrates using the second generatio n Ba(hfa)(2) tetraglyme and Ca(hfa)(2) tetraglyme (hfa denotes hexaflu oroacetylacetonate), and the Cu(acac)(2) (acac denotes acetylacetonate ) as volatile metal-organic precursors. BaCaCu precursor films of comp osition 2:2:3 were annealed in the presence of a mixture of thallium ( III), barium, calcium and copper oxides at temperatures of 840-860 deg rees C and oxygen partial pressure varying from 0.04-0.5 atm. The form ation of an oriented Tl1+xBa2Ca2Cu3O9+x (x approximate to 0.5) intergr owth structure has been observed in narrow temperature and oxygen part ial pressure ranges. The electrical resistivity data show T-c0 = 101 K which, in accordance with the scanning electron microscopy image, app ears indicative of a material with weakly linked grains.