Vaporization behavior of neptunium mononitride

Vaporization behavior of NpN(s) was investigated by mass spectrometry with a Knudsen-cell in the temperature range of 1690-2030 K. It is suggested from the vapor pressure measurements that NpN(s) decomposed into Np(1) and N-2(g). The free energy of formation of NpN(s) was evaluated by using the partial pressures of Np(g), the decomposition pressures of N-2(g) reported previously and the free energy of formation of Np(g). The free energy of formation of NpN(s) obtained lay between those of UN and PuN reported in the literature. (C) 1997 Elsevier Science B.V.