Synthesis of UO₂ and ThO₂ doped with Gd₂O₃

Uranium dioxide (urania, UO₂) and thorium dioxide (thoria, ThO₂) doped with gadolinium oxide (gadolinia, Gd₂O₃) were prepared via solid-state synthesis. For Gd₂O₃-doped ThO₂, also an alternative, semi-dry process ("suspension coating") was applied in which Gd₂O₃-coated ThO₂ powder was produced via suspension drying followed by calcination. The microstructure and homogeneity of the materials were investigated by ceramography, EPMA and XRD. Solid-state synthesis is a convenient method to produce Gd₂O₃-doped UO₂. However, this route was found to be inappropriate to obtain Gd₂O₃-doped ThO₂ with an acceptable microstructure and homogeneity. The suspension coating process reported in this work is a simple and practical method to overcome these issues