Natroboltwoodite (synthetic): Crystal structure and Raman spectroscopy

[Marco E. Ciriotti]

Referenza:
▪ Plášil, J., Škoda, R., Fatkova, K. (2022): Crystallization of Uranyl Silicate Natroboltwoodite during an Experimental Dissolution of the Mineral Yttrialite-(Y): Crystal Structure and Raman Spectroscopy. Crystal Growth & Design, 22, (in press).

Abstract:
A synthetic analogue of the mineral natroboltwoodite was obtained unprecedently during a dissolution experiment with the mineral yttrialite-(Y), at a temperature of 200 °C, pressure ∼1.5 MPa, and strongly alkaline conditions. Natroboltwoodite formed along with analcime and aegirine. Single crystals of natroboltwoodite obtained allowed us to reveal its crystal structure for the first time. It differs from the other known uranyl silicate structures in the size of its respective unit-cell volume. The increased size of the structure corresponds to the positional and occupational disorder among one of the Si-tetrahedrally coordinated sites. On the basis of structural complexity parameters, a comparison involving both known synthetic and naturally occurring uranyl silicates is provided and discussed.