Synthesis, characterization and thermal expansion measurements on uranium–cerium mixed oxides

Uranium–cerium mixed oxides (U1−yCey)O2 (y = 0.2, 0.4, 0.6, 0.8) were prepared by combustion synthesis using citric acid as the fuel. Sintering of the solid solutions was carried out at 1873 K under reduced atmosphere. From the room temperature XRD patterns of the sintered samples it was found that the solid solutions form single phase fluorite structure. The room temperature lattice parameters of (U1−yCey)O2 (y = 0.2, 0.4, 0.6, 0.8) are 0.5458, 0.5446, 0.5434 and 0.5422 nm respectively. Thermal expansion of (U1−yCey)O2 (y = 0.2, 0.4, 0.6, 0.8) in the temperature range 298–1973 K was measured by high temperature X-ray diffraction (HTXRD). The coefficients of thermal expansion increase with increase in CeO2 content in the sample and the measured data in the temperature range 298–1973 K, for (U1−yCey)O2 (y = 0.2, 0.4, 0.6, 0.8) are 18.23, 19.91, 21.59, 23.29 × 10−6 K−1, respectively.