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Phase development of Tl2Ba2CaCu2O8 thin films on LaAlO3 substrates

1993; American Institute of Physics; Volume: 62; Issue: 23 Linguagem: Inglês

10.1063/1.109149

1520-8842

M. Lanham, T. W. James, M. M. Eddy, F. F. Lange, David Clarke,

Iron-based superconductors research

The evolution of phases leading to the formation of epitaxial films of nominal composition Tl2Ba2CaCu2O8 on (100) LaAlO3 by post-deposition annealing of amorphous precursor films has been investigated by examining interrupted heat-treatment samples using analytical microscopy and x-ray diffraction. The superconductor, with a composition of Tl1.8Ba2Ca0.94Cu2.6Ox, forms from a melt, which itself formed from intermediary crystalline phases during the continual loss of Tl2O. It is concluded that Tl1.8Ba2Ca0.94Cu2.6Ox, Cu2O, and Tl3Ca5Ox are in subsolidus equilibrium and that a melt phase exists between at least 780 and 860 °C under reducing conditions controlled by the Tl2O vapor.