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Abstract

Neptunium dioxide has been treated in reducing and oxidising 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.

Additional information

Authors: RICHTER K, JRC ISPRA ESTAB. (ITALY);SARI C JRC ISPRA ESTAB. (ITALY), JRC ISPRA ESTAB. (ITALY)
Bibliographic Reference: JOURNAL OF NUCLEAR MATERIALS, VOL. 148 (1987), PP. 266-271
Record Number: 1989126019901 / Last updated on: 1989-01-01
Category: PUBLICATION
Available languages: en