Superconducting Tl-Pb-Ba-Sr-Ca-Cu-O(Ag) thick films (5-20 /spl mu/m) prepared using a commercial spray pyrolysis system and 2-zone furnace annealing

摘要

A spray pyrolysis route to superconducting Pb-, Sr-, and Ag-substituted Tl-Ba-Ca-Cu-O thick films has been developed. First, a precursor powder with the stoichiometry Pb/sub 0.46/Ba/sub 0.40/Sr/sub 1.52/Ca/sub 1.86/Cu/sub 3.00/O/sub x/(Ag/sub /0/sub .37/) (PBSCCO) was synthesized with the particle size of this powder being subsequently reduced to 4-6 /spl mu/m using a ball mill. Next, this powder was mixed with ethyl cellulose binder and sprayed with an airbrush using an N/sub 2/ carrier gas, polycrystalline Y/sub 2/O/sub 3/:ZrO/sub 2/ (YSZ) as single-crystal MgO, SrTiO/sub 3/, NdGaO/sub 3/, and LaAlO/sub 3/ substrates were mounted on a hot plate with typical growth temperatures of 80-100 /spl deg/C. Growth times of /spl sim/10 min provided films which were 5-20 /spl mu/m in thickness. After an intermediate O/sub 2/ anneal to remove the organic binder, these films were subjected to a flowing 2-zone thallination process. Very well c-axis oriented Tl/sub 0.70/Pb/sub 0.36/Ba/sub 0.39/Sr/sub 1.58/Ca/sub 1.98/Cu/sub 3/O/sub x/ (TP-1223) phase material was obtained for films grown on single-crystal LaAlO/sub 3/. Films grown on all other substrates surveyed in the study gave rise to impurity phase formation and/or incomplete reaction. The PBSCCO and TP-1223 films were characterized by /spl theta//2/spl theta/ and /spl omega/-rocking curve X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM), variable temperature magnetic measurement, and inductively coupled plasma atomic emission spectroscopy (ICPAES).