One-Pot Synthesis, X-Ray Diffraction and MAS NMR Spectroscopic Study of Gallosilicate Nitrate Cancrinite Na₈[GaSiO₄]₆(NO₃)₄(H₂O)₆

Abstract

One-pot synthetic gallosilicate nitrate cancrinite (CAN) framework topology have been synthesized under hydrothermal conditions at 100 °C. The synthesized product was characterized by, X-ray powder diffraction, IR, Raman and ²⁹Si, ²³Na MAS NMR spectroscopy, SEM and thermogravimetry. The crystal structure refinement of pure nitrate cancrinite has been carried out from X-ray data using Rietveld refinement method. Gallosilicate cancrinite Na₈[GaSiO₄]₆(NO₃)₄(H₂O)₆ crystalline hexagonal with space group P6₃ and a = 12.77981 Å (2), c = 5.20217 Å (1), (R_wp = 0.0696 R_p = 0.0527). The results by MAS NMR spectroscopy confirmed the alternating Si, Ga ordering of the gallosilicate framework for a Si/Ga ratio of 1.0. A distribution of the quadrupolar interaction of the sodium cations caused by the enclatherated water molecules and motional effects can be suggested from the ²³Na MAS NMR. Thermogravimetric investigation shows the extent of nitrate entrapment, stability within the cancrinite cage and decomposition properties. SEM clearly shows the hexagonal needle shaped crystals of nitrate cancrinite.