Encapsulation of volatile fission products by the intermetallic electride Sr3CrN3:e–

Abstract

Electrides are characterized by their unique structural architectures, where excess electrons are trapped in specific sites such as cages, channels, or layers within the lattice. The trapped electrons have significant potential for trapping volatile fission products, especially anionic species such as Br, I, and Te, released during spent nuclear fuel reprocessing. Here, density functional theory simulations are used to investigate the encapsulation efficacy of various volatile fission products, including Kr, Xe, Br, I, Te, Rb, and Cs, in a recently identified one-dimensional Sr3CrN3:e− electride and compare to values in Ca3CrN3:e− and Ba3CrN3:e−. It is shown that the encapsulation energies for Kr, Xe, Rb, and Cs are endothermic, indicating that these species are unstable when encapsulated within this electride. In contrast, the encapsulation of Br, I, and Te is highly exothermic, suggesting that the process is energetically favorable for these anions. Additionally, when homonuclear dimers (Br2, I2, and Te2) are encapsulated, the simulations predict dissociation within the electride lattice, forming pairs of adjacent anions instead of intact molecules.