Tl-based superconducting films prepared by aerosol spray deposition and thallinated in an open system |
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Authors: | Zuzana Matkovičová Vladimír Štrbík Gustav Plesch Michaela Valeriánová Agáta Dujavová |
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Institution: | (1) Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, SK-84215 Bratislava, Slovakia;(2) Institute of Electrical Engineering, Slovak Academy of Science, SK-84104 Bratislava, Slovakia |
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Abstract: | Superconducting Tl-based films were prepared on a LaAlO3 single crystal substrate. Spray pyrolysis of Ba, Ca and Cu nitrate solutions was used for deposition of the precursor films.
They were subsequently ex-situ thallinated in flowing oxygen (open system). While the superconducting Tl-2212 phase formed at an annealing temperature
of 880°C, thallination at 900°C led to the formation of a Tl-2223 /Tl-2212 mixture. The amount of Tl-2223 increased with prolonged
thallination, whereas the Tl-2212 phase progressively disappeared. Films prepared in such a manner were c-oriented and contained only low amounts of non-superconducting impurities. The resulting samples were characterized by XRD
and SEM and their T
C
values were determined by resistive four-point measurements. They showed critical temperatures in the range of T
ON
= 125–135 K, T
C0 = 91–93 K. Differences between the composition and properties of the obtained films and those thallinated in closed systems
under 50 kPa of oxygen are discussed in this paper. Results show that the Tl-2212 → Tl-2223 transformation proceeds at a slower
rate under flowing oxygen than in a closed system.
Presented at 5-th International Conference Solid State Surfaces and Interfaces, November 19–24, 2006, Smolenice Castle, Slovakia. |
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Keywords: | Tl-based superconducting film spray pyrolysis Tl-2212 Tl-2223 |
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