Reaction synthesis of SrTiO3 mineral-like ceramics for strontium-90 immobilization via additional in-situ synchrotron studies

The paper presents spark plasma sintering-reaction synthesis (SPS-RS) of SrTiO3-based mineral-like ceramics with a perovskite structure, which is promising for immobilization of Sr-90 radionuclides. Detailed time-resolved study of phase transformations taking place in the reactive mixture (SrCO3 and TiO2) within 20–1000 °C temperature range was conducted using both in situ heating synchrotron XRD and TGA. Structure and composition dependence on consolidation temperature was revealed by the means of SEM and EDX. We determined optimal temperature conditions for rapid formation of SrTiO3 ceramics with density – 4.49 g cm−3, Vickers hardness – up to 6.2 GPa, compressive strength – 279 MPa, and strontium leaching rate of 10−5–10−6 g cm−2·day. These results clearly show strong applied potential of the presented material for radioactive waste management and isotope production fields.