Cs2USi6O15: A Tetravalent Uranium Silicate

A uranium(IV) silicate has been synthesized under high-temperature, high-pressure hydrothermal conditions. The structure consists of unbranched dreier single layers with the composition [Si2O5] that are connected by UO6 octahedra to form a 3D framework with 7-ring channels where the Cs+ cations are located. Each UO6 octahedron spans four neighboring dreier single chains and, therefore, introduces a high degree of corrugation in the silicate layers. The U 4f X-ray photoelectron spectroscopy spectrum was measured to confirm the valence state of the uranium. A comparison of related metal silicate structures is made. After the synthesis of this compound, all members in the family of uranium silicates and germanates with oxidation states of uranium from 4+ to 6+ have been observed.