Insights into the Phase Relations in a U-N System Using a Cluster Formula.

Despite the fact that five kinds of uranium nitrides, i.e., uranium mononitrides (UN, R3̅m and Fm3̅m), a uranium dinitride (UN, Fm3̅m), and uranium sesquinitrides (α-UN, Ia3̅; β-UN,P3̅m1), have been confirmed, until now the phase relations are not well understood because of the puzzling nonstoichiometric issue.