Hydrothermal synthesis, characterization and structure refinement of chlorate- and perchlorate-sodalite |
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Authors: | Th Veit J-Ch Buhl W Hoffmann |
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Affiliation: | Institute of Mineralogy, University of Münster, Corrensstr. 24, D-4400 Münster Federal Republic of Germany |
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Abstract: | Chlorate- and perchlorate-sodalites were synthesized hydrothermally in the temperature range of 160°C to 500°C. IR absorption bands indicate the enclathration of NaClO3 (624 cm?1) and NaClO4 (624 cm?1 and 2050 cm?1) in the sodalite cages. The thermal decomposition has been characterized by simultaneous thermal analysis (TG, DTG, DTA) and high temperature X-ray powder diffraction. The total collapse of the sodalite framework structure and the formation of nepheline could be observed at 750°C and 1100°C for chlorate-sodalite and perchlorate-sodalite, respectively. The crystal structure has been determined for NaClO4-sodalite showing cubic symmetry (a0=9.071 Å, SG P
3n) and complete ordering of Si and Al in the silicate framework; the Si-O-Al angle is 146.7°. The Cl atoms of the enclathrated perchlorate are located at the central positions of the sodalite cages. For the oxygen atoms of the Cl4? anions the structure refinement led to orientationally disordered sites having a close resemblance to the well-known O(2) positions of basic sodalite Na8AlSiO4]6(OH)2·2 H2O. |
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