SUPERCONDUCTING TL-PB-BA-SR-CA-CU-O(AG) THICK-FILMS (5-20 MU-M) PREPARED USING A COMMERCIAL SPRAY-PYROLYSIS SYSTEM AND 2-ZONE FURNACE ANNEALING

A spray pyrolysis route to superconducting Pb-, Sr-, and Ag-substitute d Tl-Ba-Ca-Cu-O thick films has been developed. First, a precursor pow der with the stoichiometry Pb0.46Ba0.40Sr1.52Ca1.86Cu3.00Ox(Ag-0.37) ( PBSCCO) was synthesized with the particle size of this powder being su bsequently reduced to 4-6 mu m using a ball mill. Next, this powder wa s mixed with ethyl cellulose binder and sprayed with an airbrush using an N-2 carrier gas. Flexible polycrystalline Y2O3:ZrO2 (YSZ) as well as single-crystal MgO, SrTiO3, NdGaO3, and LaAlO3 substrates were moun ted on a hot plate with typical growth temperatures of 80-100 degrees C. Growth times of similar to 10 min provided films which were 5-20 mu m in thickness. After an intermediate O-2 anneal to remove the organi c binder, these films were subjected to a flowing 2-zone thallination process. Very well c-axis oriented Tl(0.70)Pb(0.36)Ba(0.39)Sr(1.58)Ca( 1.98)Cu(3)0(x) (TP-1223) phase material was obtained for films grown o n single-crystal LaAlO3. Films grown on all other substrates surveyed in the study gave rise to impurity phase formation and/or incomplete r eaction. The PBSCCO and TP-1223 films were characterized by theta/2 th eta and omega-rocking curve X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM), variable temperature magnetic measurement, and inductively coupled plasma atomic emission spectroscopy (ICPAES).