Crystal Structure of Mixed Np(V)-Ammonium Carbonate

• Published in: Symmetry (Basel) Vol. 14; no. 12; p. 2634
• Main Authors: Nevolin, Iurii M, Petrov, Vladimir G, Grigoriev, Mikhail S, Averin, Alexei A, Shiryaev, Andrey A, Krot, Anna D, Maslakov, Konstantin I, Teterin, Yury A, Fedoseev, Alexander M
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.12.2022
• Subjects: Actinides; Ammonia; Ammonium compounds; Ammonium paratungstate; Aqueous solutions; Carbonates; Chemical reactions; Crystal structure; Crystallography; Crystals; Diffraction; Environment models; hydrothermal synthesis; Hydrothermal treatment; Lasers; Neptunium; Nuclear energy; Nuclear fuel cycle; Nuclear industry; Photoelectrons; Radiation; Radioactive substances; Radioactive waste disposal; Radiochemistry; Sensors; Single crystals; Spent nuclear fuels; structural investigations; Structure; Symmetry; X ray photoelectron spectroscopy; X-ray diffraction; X-rays; Russia; United Kingdom > UK; United States > US
• ISSN: 2073-8994; 2073-8994
• DOI: 10.3390/sym14122634

This work presents details of the synthesis, properties and structure of a novel neptunium carbonate (NH4)[NpO2CO3], a member of the M[AnO2CO3] (M = K, (NH4), Rb, Cs) class of compounds. Carbonates play an important role in the migration of actinides in the environment, and thus are relevant for handling and disposal of radioactive wastes, including spent nuclear fuel and vitrified raffinates. Knowledge of the crystallographic structure of these compounds is important for models of the environmental migration behavior based on thermodynamic descriptions of such chemical processes. (NH4)[NpO2CO3] crystals were obtained during long-term hydrothermal treatment of Np(VI) in aqueous ammonia at 250 °C. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) show that a single-phase sample containing only Np(V) was obtained. Structural features of (NH4)[NpO2CO3] were elucidated from single crystal X-ray diffraction and confirmed by vibrational spectroscopy. The results obtained are of interest both for fundamental radiochemistry and for applied problems of the nuclear fuel cycle.