Synthesis and Characterization of a New Aluminogermanate Thiocyanate Aluminogermanate Sodalite Na8[AlGeO4]6(SCN)2

Abstract

Thiocyanate enclathrated sodalite with aluminogermanate host framework was obtained by high temperature hydrothermal synthesis at 423 K. X-ray power diffraction, IR, ESR, TGA, SEM, and NMR spectroscopy on 27Al and 23Na nuclei were used to characterize this new sodalite. The crystal structure of aluminogermanate, Na8[AlGeO4]6(SCN)2 sodalite was refined from X-ray powder diffraction data in the space group P$$\bar {4}$$3n: a = 9.239 A, V = 788.630 A3, Rwp = 0.8515, Rp = 1.3241, and Al–O–Ge angle is 136.820°. The 27Al MAS NMR study confirms alternating Ge and Al ordering in sodalite framework. The recorded infrared spectrum show absorption band typical for the sodalite structure and frequency at 2200 cm–1 also clearly indicate the incorporation of thiocyanate anions in the sodalite cage. Thermogravimetric analysis has provided information on the extent of thiocyanate entrapment, stability within the sodalite cage and decomposition properties. SEM study shows the retention of cubical morphology of the thiocyanate enclathrated sodalite.