CHEMICAL ASPECTS OF THE PREPARATION OF HIGH T-C SUPERCONDUCTING TL-BA-CA-CU-O FILMS BY DEPOSITION FROM AEROSOL

Superconducting Tl2Ba2CaCu2Ox, (2212) films have been prepared by anne aling the precursor Ba-Ca-Cu-O thin layers in an atmosphere containing vapours of thallous oxide. The precursor films were deposited from aq ueous aerosol of the corresponding nitrates onto MgO substrates. As a source of Tl2O thallination pellets prepared by homogenizing of a mixt ure of Ba-Ca-Cu-O precursors with Tl2O3 were used. After common anneal ing of the film and the thallination pellet, which were in close conta ct, superconducting (2212) phase was obtained in the him as well in th e pellet. The best T-c values of the synthesized (2212) films and pell ets were 103.5 and 102 K, respectively. The chemical aspects of both t hermal decomposition reactions during film growing as well as those pr oceeding during the thallination process, are discussed from the point of view of thermogravimetric TG, DTG and DTA measurements. (C) 1997 E lsevier Science B.V.