Solid solutions of hydrogen uranyl phosphate and hydrogen uranyl arsenate. A family of luminescent, lamellar hosts

Hydrogen uranyl phosphate, HUO/sub 2/PO/sub 4/ /times/ 4H/sub 2/O (HUP), and hydrogen uranyl arsenate, HUO/sub 2/AsO/sub 4/ /times/ 4H/sub 2/O (HUAs), form solid solutions of composition HUO/sub 2/(PO/sub 4/)/sub 1-x/(AsO/sub 4/)x (HUPAs), representing a family of lamellar, luminescent solids that can serve as hosts for intercalation chemistry. The solids are prepared by aqueous precipitation reactions from uranyl nitrate and mixtures of phosphoric and arsenic acids; thermogravimetric analysis indicates that the phases are tetrahydrates, like HUP and HUAs. Powder x-ray diffraction data reveal the HUPAs solids to be single phases whose lattice constants increase with X, in rough accord with Vegard's law Spectral shifts observed for the HUPAs samples. Emission from the solids is efficient (quantum yields of /approximately/ 0.2) and long-lived (lifetimes of /approximately/ 150 /mu/s), although the measured values are uniformly smaller than those of HUP and HUAs; unimolecular radiative and nonradiative rate constants for excited-state decay of /approximately/ 1500 and 5000 s/sup /minus/1/, respectively, have been calculated for the compounds. 18 refs., 5 figs., 2 tabs.