Phase relationships in the neptunium-oxygen system
Abstract
Neptunium dioxide has been treated in reducing and oxidizing atmospheres between 570 and 2880 K. The results of ceramographic, X-ray diffraction, thermal and electron microprobe analysis were used to construct a partial neptunium-oxygen phase diagram. The highest valency of neptunium in oxides is four at temperatures above 900 K. The dioxide exhibits a hypostoichiometric homogeneity range (NpO 2-x) at temperatures above 1300 K; on cooling to room temperature hypostoichiometric compositions decompose into NpO 2 and metallic Np. The neptunium-oxygen system shows characteristics which are intermediate between those of the isotype uranium-oxygen and plutonium-oxygen systems.
- Publication:
-
Journal of Nuclear Materials
- Pub Date:
- May 1987
- DOI:
- 10.1016/0022-3115(87)90019-5
- Bibcode:
- 1987JNuM..148..266R