Partitioning of rhodium and ruthenium between Pd-Rh-Ru and (Ru,Rh)O2 solid solutions in high-level radioactive waste glass

The partitioning of rhodium and ruthenium between Pd-Rh-Ru alloy with a face-centered cubic (FCC) structure and (Ru,Rh)O2 solid solution has been investigated between 1273 and 1573 K at atmospheric oxygen fugacity. The rhodium and ruthenium contents in FCC increase, while the RhO2 content in (Ru,Rh)O2 decreases with increasing temperature due to progressive reduction of the system. Based on the experimental results and previously reported thermodynamic data, the thermodynamic mixing properties of FCC phase and (Ru,Rh)O2 have been calibrated in an internally consistent manner. Phase equilibrium of platinum grope metals in an HLW glass was calculated by using the obtained thermodynamic parameters.