The three new solid-state compounds BaThTe4, BaUTe4, and BaUTe6 have been synthesized and characterized. BaThTe4 and BaUTe4 are isostructural. The structure consists of infinite ∞2[AnTe42-] layers separated by Ba2+ ions. Each An (An = Th, U) atom is coordinated to eight Te atoms in a bicapped trigonal-prismatic arrangement. Te atoms are connected to each other to form linear infinite chains. These Te-Te interactions are longer than that of a Te-Te single bond. However, this structure also possesses Te-Te single bonds. Charge balance in the formula BaAnTe4 may be achieved with [Ba2+]2[(An4+)2(Te2-)2(Te22-)(Te23-)2]4-. The structure of BaUTe6 features one-dimensional anionic ∞1[UTe62-] chains that are separated by Ba2+ ions. There are three Te-Te single bonds around each U atom. The anion in this structure can thus be described as [U4+(Te22-)3]2-. Resistivity measurements on single crystals of BaThTe4 and BaUTe6 show semiconducting behavior. DFT calculations indicate finite band gaps for BaThTe4 and for BaUTe6, whereas BaUTe4 has a vanishing density of states at the Fermi level.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry