7 research outputs found
Sosedka pegmatite body at the Malkhan deposit of gem tourmaline, Transbaikalia: Composition, inner structure, and petrogenesis
Low-pressure (> 4 MPa) and high-temperature (> 1250 °C) incongruent melting of marly limestone: formation of carbonate melt and melilite–nepheline paralava in the Khamaryn–Khural–Khiid combustion metamorphic complex, East Mongolia
The mineralogy and geochemistry of quartz-tourmaline schlieren in the granites of the Primorsky Complex, Western Baikal Region
Impeding Tc-99(IV) mobility in novel waste forms
Technetium (Tc-99) is an abundant, long-lived radioactive fission product whose mobility in the subsurface is largely governed by its oxidation state. Tc immobilization is crucial for radioactive waste management and environmental remediation. Tc(IV) incorporation in spinels has been proposed as a novel method to increase Tc retention in glass waste forms during vitrification. However, experiments under high-temperature and oxic conditions show reoxidation of Tc(IV) to volatile pertechnetate, Tc(VII). Here we examine this problem with ab initio molecular dynamics simulations and propose that, at elevated temperatures, doping with first row transition metal can significantly enhance Tc retention in magnetite in the order Co>Zn>Ni. Experiments with doped spinels at 700 degrees C provide quantitative confirmation of the theoretical predictions in the same order. This work highlights the power of modern, state-of-the-art simulations to provide essential insights and generate theory-inspired design criteria of complex materials at elevated temperatures.11Ysciescopu