Reproducible synthesis by metal-organic chemical vapour deposition and thallium vapour diffusion of oriented thin-films : intergrowth of and structures

Superconducting thin-films containing randomly disordered layers of and have been synthesized through a combined approach of metal-organic chemical vapour deposition (MOCVD) and thallium vapour diffusion. The BaCaCu matrices have been deposited onto yttria stabilized zirconia (YSZ) substrates using the second generation tetraglyme and tetraglyme (hfa denotes hexafluoroacetylacetonate), and the (acac denotes acetylacetonate) as volatile metal-organic precursors. BaCaCu precursor films of composition 2:2:3 were annealed in the presence of a mixture of thallium (III), barium, calcium and copper oxides at temperatures of 840 - and oxygen partial pressure varying from 0.04 - 0.5 atm. The formation of an oriented () intergrowth structure has been observed in narrow temperature and oxygen partial pressure ranges. The electrical resistivity data show which, in accordance with the scanning electron microscopy image, appears indicative of a material with weakly linked grains.