Optical characterization of Tl-based superconducting films deposited from aerosol

Superconducting Tl-based films were prepared by deposition of precursor Ba-Ca-Cu films from an aerosol generated ultrasonically, followed by an annealing in a thallium vapour. As substrates we used single crystalline yttrium-stabilized zirconia (YSZ). The prepared films were about 3 μm thick. Annealed films consisted of 2212 and 2223 phases and partially of an amorphous phase, as revealed by X-ray and Raman spectroscopy. Hence, lower T_c values were obtained, from the interval 85-105 K. The Raman spectra measurements show the presence of peaks similar to those previously reported for the 2212 phase, with, however, some shifts in energy, which could be related to the presence of the 2223 phase and thus to the strengthening of the chemical bonds.