Raman spectroscopic characterization of the copper, cobalt, and nickel selenites: Synthetic analogs of chalcomenite, cobaltomenite, and ahlfeldite

<p>Raman spectroscopy has been used to study synthetic analogs of the minerals chalcomenite, cobaltomenite, and ahlfeldite occurring in nature. The results obtained are compared with the spectra of these minerals. In general, the majority of vibrational bands of synthetic species are in good agreement with natural chalcomenite, cobaltomenite, and ahlfeldite. The noticeable discrepancies are found for the bands assigned to the deformation mode of selenite groups. A better signal-to-noise ratio realized with synthetic species aids in comprehensive analysis of the spectra, especially in the region of water bands.</p

Mixed Uranyl Sulfate–Selenates: Evolution of Structural Topology and Complexity vs Chemical Composition

Phase formation in the aqueous system of uranyl nitrate, potassium hydroxide, and variable amounts of sulfuric and selenic acids has been investigated. Four different types of crystalline phases with variable S and Se contents were isolated and characterized using single-crystal X-ray diffraction (XRD) and IR spectroscopy. Topological analysis and information-based complexity calculations demonstrated the following: (a) the absence of a continuous solid solution in the system, (b) the absence of isotypic sulfate and selenate phases, and (c) the discovery of two layered topologies unprecedented among inorganic oxysalts