Band theoretical results within the density functional theory are reported for the uranates K2UO4 and Na4UO5. The two structures are differentiated respectively by uranyl and reverse uranyl-type short U-O distances characterizing the UO6 octahedra, as also reflected by larger compressibility and stability of the potassium-based uranate derived from energy-volume equations of states and the cohesive energy. A larger ionic character of Na4UO5 is inferred from comparative Bader charge analyses. The two uranates are insulators with a larger band gap and less extended valence and conduction bands for Na4UO5. Chemical bonding shows major interactions for U-O versus Na,K-O and is further differentiated as a function of the distances. The band structure results confirm the hexavalent character of the uranium atoms.
Graphical Abstract
Ab-initio Studies of the Electronic Structures of the Hexavalent Uranium Compounds K2UO4 and Na4UO5
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