Metastability of Superconducting Compounds in the Y-Ba-Cu-O System

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Science  09 Apr 1993:
Vol. 260, Issue 5105, pp. 196-198
DOI: 10.1126/science.260.5105.196


Precision isothermal solution calorimetry was used to determine the standard-state enthalpy of formation of a number of phases in the Y-Ba-Cu-O system. An analysis of the data indicates that YBa2Cu4O8 is thermodynamically metastable under ambient conditions. Taken together with the results from previous investigations, these data show that all of the superconducting compounds in the Y-Ba-Cu-O system are thermodynamically metastable at low temperatures.