Toru Sugawara

Empirical relationships between temperature, pressure, and MgO content in olivine and pyroxene saturated liquid

From a large number of experimental data on olivine-liquid and pyroxene-liquid equilibria, it is revealed that there is a linear relationship between the mole percent of MgO in olivine and/or pyroxene saturated liquid, temperature and pressure. The effect of dissolved water content on the linear relationship has also been taken into account based on recently reported experimental data in the hydrous systems. The linear equation allows one to calculate the temperature from the MgO content and pressure or the MgO in the liquid from the temperature and pressure. The standard deviations of calculated temperature and MgO content of the anhydrous liquid are about ±30°C and within 3 mol%, respectively. The standard deviation of the temperature is the same or less than those of previously reported geothermometers. This geothermometer has the advantage that it is unnecessary to know the FeO content of the liquid or oxygen fugacity.

Phase equilibrium experiments on the simulated high-level waste glass containing platinum group elements

Phase equilibrium experiments for the simulated high-level waste (HLW) glass containing palladium, rhodium and ruthenium discharged from a full scale mock up melter have been carried out between 1073 and 1473 K under air and CO2 atmosphere. The chemical compositions of Pd–Rh–Ru–Te (Pd metal phase) and (Ru, Rh)O2 (Ru oxide phase) solid solutions and glass matrix were measured by electron probe micro analysis. Palladium content in the Pd metal phase decreased and ruthenium content in the Ru oxide phase increased with increasing temperature and decreasing oxygen fugacity due to progressive reduction of rhodium. The chemical compositions of these crystalline phases are independent of that of borosilicate glass matrix. Partition coefficient of rhodium between Pd metal phase and Ru oxide phase (KRh) can be expressed by where T and represent absolute temperature and oxygen fugacity. Based on the comparison of crystal compositions in the HLW glass with experimental results, it can be expected that the HLW glass examined in this study had been equilibrated in the temperature range from 1273 to 1373 K and oxygen fugacity close to that of air just before discharging from the melter.