H-Isotopes Solubility in Sn-Li Alloys: A Theoretical Calculation from Thermodynamic Data

The H (or D, or T) Sievert's constant for liquid Sn-Li alloys is calculated from thermodynamic data issuing of the Sn-Li binary phase diagram analysis. The range of temperatures investigated is 600-873 K (Sn_0.8Li_0.2 m.p. ~ 599 K) to maintain single-phase binary melts. The thermodynamic functions of Li-H, Sn-H, Sn-Li are evaluated to derive those of Sn-Li-H. Thus, monotectic solubility data for Sn and Li is analyzed. The calculation is done for high-dilution conditions. A quasi-chemical regular solution model is used for temperature/composition extrapolations when no data is available. The tritium Sievert's constant in Sn_0.8Li_0.2 at 600 K is: 9.65 10^-8 Pa^-12, five times the Reiter's measured value for Pb-17Li and ~ 6 times the value in Pb-17Li eutectic obtained by using the same theoretical approach.