Study on the development of the lattice strain in (Mg,U)O _2+x solid solution

Lattice strain observed in magnesia-doped UO ₂ was studied. Solid solution Mg _y U _1-y O _2+x was prepared by the reaction of mixtures of MgUO ₄ , MgU ₃ O ₁₀ and UO ₂ . The composition of the solid solution was analysed by X-ray diffraction (XRD) and electron probe microanalysis. Homogeneous and inhomogeneous strains were evaluated by XRD analysis. The homogeneous strain was explained as caused by the cation defects in the solid solution. The development of the strain was dependent on the number of Mg ²⁺ -U ⁵⁺ complexes. The variance method was applied to obtain the inhomogeneous strain. The average crystallite size of the product was also given in the variance analysis. The evolution of the inhomogeneous strain and the decrease in the size of the crystallite were attributed to the precipitation of MgO accompanied by the reduction of the sample.