The activity and diffusivity of O in the liquid high-temperature superconductor precursor alloy were measured by using a modified coulometric titration method at 913 to 957C. The standard Gibbs formation energies, and the diffusivity of O in the liquid under 1atm of 1at%O, were found to be described by:

G(kJ/mol) = -655.20 + 0.335T

and:

D(cm2/s) = 0.018 exp[-48100/RT]

In spite of a very strong bonding of O to the liquid alloy, the diffusivity of O was of the order of 0.0001cm2/s. The solubilities of O in the liquid alloy were of the order of 0.0145 and 0.017at% at 913 and 935C, respectively.

H.Chou, H.S.Chen, W.C.Fang, F.A.Thiel, M.K.Wu: Applied Physics Letters, 1992, 60[6], 760-2