Evaluation of chemical bonding and electronic structures in trisodium actinate for actinide series from thorium to curium

• Published in: Computational materials science 2020-09, Vol.182, p.109770, Article 109770
• Main Authors: Xu, Zhong-Fei, Hu, Shu-Xian, Yang, Yu, Zhang, Ping
• Format: Article
• Language: English
• Subjects: Bonding feature; Electronic structure; First-principles calculation; Trisodium actinate
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2020.109770

[Display omitted] Despite growing interest in actinide (An) complexes and their bonding chemistry in recent years, the characteristics of the chemical bonding of actinides in solid-state compounds remain to be relatively unclear compared with those of molecular complexes. Herein, we systematically characterized the structural and electronic properties of trisodium actinates [Na3AnO4 (An = Th to Cm)] using first-principles theoretical methods. In general, the band structures exhibit a transition from charge-transfer insulator with the p-d band gap type to Mott-insulator with the f-f band gap type at Na3PuO4. The conjugation effects of actinide contraction and the decreased energy of the 5f bands in these compounds are responsible for the transition. Consistently, the pentavalent An ions can be achieved from Pa to Pu, and then upon the reduction of the 5f atomic orbitals, strong spin polarization leads to tetravalent Am(f5)IV and Cm(f6)IV. These results improve our knowledge of the OS of actinides in solid-state compounds and establish the connection among local structure, chemical composition, and properties for understanding the underlying mechanism of An chemical state in actinide materials for specific applications.