Synthesis, temperature-dependent X-ray diffraction and Raman spectroscopic characterization of the sodalite to nosean phase transformation of I Na7.7(1)( MnO4)1.7(2)(H2O)0.8(2)|[AlSiO4]6

Investigations of hydrothermal synthesis in the basic Na2O-Al2O3-SiO2-MnO4-H2O -system with variations of synthesis temperature and NaOH concentration were carried out. A permanganate bearing sodalite vertical bar Na-7.7(1)(MnO4)(1.7(2))(H2O)(0.8(2))vertical bar[AISiO(4)](6) could be obtained. The crystal structure and temperature dependent behavior of this sodalite was examined by TG-DTA, in -situ temperature-dependent (TD) PXRD and Raman spectroscopy. Two phase transitions were observed: The first one at 600 K raises the symmetry from 13713n to Pinn due to the thermal expansion leading to a fully expanded framework. The second one at 900 K lowers the symmetry to P23, which is driven by the thermal decomposition reaction of the MnOi ion, resulting in different fillings of the (nearest) neighboring cages forming a respective nosean type structure. The templat-framework interactions were examined by temperature-dependent pre-resonance Raman spectroscopy and show the blocking of the template vibration through stronger template-framework interactions representing a solid state below ambient temperatures, whereas at elevated temperature the interaction strength decreases leading to a quasi -liquid single molecule template behavior. (C) 2017 Elsevier Inc. All rights reserved.