Isomorphism between Alkali Metals in Cavities of the Mixed Framework of (Cs0.8Rb0.2)4(NbO)2[Si8O21] Synthesized under Mild Hydrothermal Conditions

• Published in: Crystallography reports 2023-12, Vol.68 (7), p.1079-1083
• Main Authors: Belokoneva, E. L., Mozgova, A. S., Volkov, A. S., Dimitrova, O. V.
• Format: Article
• Language: English
• Subjects: Alkali metals; Cesium; Crystal structure; Crystallography and Scattering Methods; High temperature; Hydrothermal crystal growth; Ion exchange; Isomorphism; Niobium compounds; Niobium oxides; Physics; Physics and Astronomy; Rubidium; Silicates; Structure of Inorganic Compounds; Synthesis
• ISSN: 1063-7745; 1562-689X
• DOI: 10.1134/S1063774523600722

Crystals of (Cs 0.8 Rb 0.2 ) 4 (NbO) 2 [Si 8 O 21 ] were prepared by mild hydrothermal synthesis; sp. gr. P , a = 6.9990(3) Å, b = 7.8273(4) Å, c = 11.0613(5) Å, α = 77.048(4)°, β = 89.809(3)°, γ = 71.996(4)°. This synthesis of niobium compounds is more feasible than the synthesis performed previously under high-temperature and high-pressure conditions. As opposed to the known Cs- and Rb-containing silicates, the isomorphous incorporation of Cs and Rb cations in two sites was observed in the new variety, which was confirmed by the structural data and crystal-chemical characteristics. This is evidence of the ion-exchange properties of the crystals of this structural type.