Synthesis of Perovskite-Like SrTiO3 Ceramics for Radioactive Strontium Immobilization by Spark Plasma Sintering-Reactive Synthesis

One of the main requirements for the strategy of the efficient development of modern radiation technologies and nuclear power engineering is the safety of using nuclear raw materials and handling its spent forms as radioactive waste. In this work, a method of spark plasma sintering-reactive synthesis of ceramic materials based on SrTiO 3 with a perovskite-like structure was implemented for the first time. Such materials are in demand as promising solid matrices for the reliable and safe immobilization of the high-energy radionuclide strontium-90. The method is based on the in situ reactive interaction of a mixture of SrO and TiO 2 oxides during heating by unipolar pulse current under the pressing pressure. The phase and elemental compositions, structure, and consolidation dynamics of the reaction mixture of oxides in the temperature range 900–1200°C were studied by X-ray powder diffraction analysis and scanning and transmission electron microscopy. The temperature was determined for the high-rate (several minutes long) formation of a ceramic of the single-phase SrTiO 3 composition with a relative density of up to 95.6%, a Vickers microhardness of up to 1010 HV, a compressive strength of up to 283 MPa, and a strontium leaching rate in the range of 10 –6 –10 –7 g/(cm 2 day).