INFLUENCE OF PROCESSING CONDITIONS OF TL-2212 SUPERCONDUCTING FILMS DEPOSITED FROM AN AEROSOL UPON THEIR T-C AND OXYGEN RAMAN MODES

Tl based 2212 films were prepared on MgO and YSZ substrates in two ste ps. First, Ba-Ca-Cu-O precursors were deposited from an aerosol, follo wed by two types of thallination and oxygenation in a single-zone reac tion chamber. Critical temperatures T-c, X-ray and oxygen related Rama n modes were measured on superconducting films. The T-c values of prep ared films varied from the interval of 95.0 to 103.5 K. We did not fin d any pronounced relation between the T-c values and a and c unit cell parameters. The Raman spectra of investigated films revealed peaks as signed to O(1), O(2) and O(3) atom vibrations, one peak determining th e degree of recrystallization from an initial amorphous phase, and pea ks originating from impurity phases. Apparently, prolonged thermal pro cessing of films creates both, metal-cation and oxygen-anion disorder as well. It seems that a well defined relation between the transition temperature T-c and the Raman shift in the O(2) vibrations exists. It is proposed, that this relation serves as an indirect indication of a lack of oxygen in the film samples. (C) 1997 Elsevier Science B.V.