Lattice thermal expansions of NpN, PuN and AmN

Takano, Masahide ; Akabori, Mitsuo; Arai, Yasuo; Minato, Kazuo 

Lattice parameters of NpN, PuN and AmN were measured by a high-temperature X-ray diffraction method from room temperature to 1478 K maximally. Linear thermal expansions of these TRU nitrides were determined as a function of temperature. The average coefficients of linear thermal expansion from 293 to 1273 K were 8.78, 11.1 and 11.210K for NpN, PuN and AmN, respectively. The instantaneous coefficients of thermal expansion at 293 and 1273 K against the reciprocal decomposition temperatures under 1 atm of nitrogen showed the approximately linear relationship for TiN, ZrN, HfN, UN, NpN, PuN. The decomposition temperature of AmN under this condition was roughly predicted to be 2700100 K from the obtained relationship.