The preparation and properties of uranium (IV) silicate

Uranium (IV) orthosilicate, corresponding to the mineral coffinite, has been synthesized by a hydrothermal procedure. Preparative conditions including precipitation techniques, temperature, pH, and U oxidation state have been investigated. USiO (sub 4) is a blue microcrystalline compound isostructural with thorite and zircon. The infrared spectrum of USiO (sub 4) shows an absorption maximum at 11.1 (sub mu ) , characteristic of isolated SiO (sub 4) (super 4-) tetrahedra. No evidence was found for hydroxyl substitution in the synthetic material. USiO (sub 4) is stable to 1,000 degrees C. in a vacuum and to 500 degrees C. in air.