Synthesis and feasibility studies of incorporating U at Ti site of Y₂Ti₂O₇ as waste immobilizing matrix

The High Level Waste (HLW) generated after nuclear power generation process still poses a challenge of safe disposal and management. Pyrochlores (A₂B₂O₆O') are widely used since these posses numerous advantages. In our earlier studies we tried incorporating U at Y site under both oxidizing and reducing conditions, however due to large charge heterogeneity and ionic radii difference we could not dope U even 2.5 mol % under oxidizing conditions. In here we have tried doping U at Ti site under air and we could successfully incorporate up to 5 mol % without any phase separation. Y₂Ti₂-xUxO₇±δ (x= 0, 0.05, 0.075, 0.1, 0.2, 0.3) were synthesized using gel combustion method with citric acid as fuel and keeping Fuel/Nitrate ratio slightly greater than 1. It was further heated at 800°C for 35 h. XRD analysis was carried out to assess the phase purity and crystal structure determination