Study of the cocrystallization of trace amounts of plutonium with neodymium and samarium dibromides in directional crystallization of their melts

For the first time, the behavior of trace amounts of plutonium was studied in directional crystallization of melts of neodymium and samarium dibromides. It was found that the behavior of bivalent plutonium in cocrystallization with NdBr2 differs sharply from the behavior of bivalent americium and europium. Whereas the cocrystallization coefficients of the latter remain constant, the cocrystallization coefficient of plutonium changes and has a maximum in the directional crystallization process of the NdBr2 melt. Trivalent plutonium does not exhibit anomalies and cocrystallizes with samarium dibromide with a constant cocrystallization coefficient equal to ∼ 0.2. The anomalous behavior of bivalent plutonium is related to its electronic structure, allowing it to form association complexes in a melt of neodymium dibromide