The CaO–CuO–TlO1.5 system and its key role in the formation of the Tl-based superconductors

The formation of Tl2Ba2Ca2Cu3Oz is conditioned by an equilibrium plane with the Tl-rich limit of the (Ca,Tl)1-xCuO2 solid solution as one of the apices. The parent phase for the latter solid solution is the binary compound Ca0.80CuO1.93. Authors report on the phase relations in the CaO-CuO and CaO-C...

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Bibliographic Details
Published in:Physica. C, Superconductivity Superconductivity, 2002-08, Vol.372-376 (Part 2), p.1191-1194
Main Authors: Phok, S, Jondo, T.K, Jorda, J.L, Galez, Ph
Format: Article
Language:English
Subjects:
Engineering Sciences
Materials and structures in mechanics
Mechanics
Physics
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Summary:The formation of Tl2Ba2Ca2Cu3Oz is conditioned by an equilibrium plane with the Tl-rich limit of the (Ca,Tl)1-xCuO2 solid solution as one of the apices. The parent phase for the latter solid solution is the binary compound Ca0.80CuO1.93. Authors report on the phase relations in the CaO-CuO and CaO-CuO-TlO1.5 systems. Emphasis is also on the thermodynamic stability and the crystallographic properties of Ca0.80CuO1.93 (space group P2/c, a=10.9456(4), b=6.3192(2), c=16.8408 angstroms and b=104.952(2) infinity). The kinetics for phase formation and decomposition have been studied. Authors show that the decomposition reaction into Ca2CuO3 and CuO, which occurs at 870 C in p(O2)=1 bar and at 720 C in vacuum, is rate limited by a 2-D process consistent with structural considerations and has an activation energy of 656 kJ/mol. 11 refs.
ISSN:0921-4534
DOI:10.1016/S0921-4534(02)00970-X