The SrMoO4 compound, a host for strontium in tailored nuclear waste ceramics, is highly stable in deionized water, NaCl, KCl, and the acidic MgCl2 under hydrothermal conditions of 100, 200 and 300°C as indicated by the fact that <0.5% strontium was released under these conditions. In Na2SO4 solution, SrMoO4 is somewhat reactive, as indicated by the release of ~2 and 6% of the original strontium and molybdenum inventories, respectively, into solution at 200 and 300°C. More molybdenum than strontium was detected in solution because of the crystallization of celestite, SrSO4. Thus, anions such as SO2-4 influence the reactivity of SrMoO4. The SrMoO4 phase was found to be least stable in CaCl2 solution as indicated by the release of 93.5, 96.1, and 100% of the strontium from the initial SrMoO4 at 100, 200, and 300°C, respectively. However, only 0.02% of the original inventory of molybdenum in SrMoO4 was detected in solution. The removal of molybdenum from solutions was due to the formation of CaMoO4 powellite as revealed by x-ray diffraction. Thus, CaMoO4 is more stable than SrMoO4 under these hydrothermal conditions. These results show that SrMoO4 is stable in Na+, K+, and Mg2+ solutions but not in Ca2+-containing solutions.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Nuclear Energy and Engineering
- Condensed Matter Physics