Solid Solutions in the System Urania—Rare‐Earth Oxides: I, UO 2 ‐GdO 1.5 ,

The extent and nature of solid solution formation in the system urania‐gadolinia were investigated. Compositions sintered in hydrogen, in argon, and in air were analyzed by chemical and X‐ray methods. Extensive solid solution exists between uranium dioxide and gadolinium sesquioxide. Some anomalies in the lattice parameters of the solid solutions are interpreted.