Studies on synthetic galloalunites AGa3(SO4)2(OH)6: Synthesis, Thermal analysis, and X-ray characterization

  • Stoichiometric end member galloalunites of the general formula AGa3(SO4)2(OH)6, with A = Na+, K+, Rb+, H3O+, and NH4+ have been synthesized under hydrothermal conditions. These galloalunites were characterized by chemical methods, thermal analysis (DSC, TG coupled with mass spectroscopy), and powder X-ray diffraction (XRD). The stages of thermal decomposition of sodium, potassium and rubidium galloalunite show a common decomposition mechanism forming β-Ga2O3 and A2SO4 (A = Na+, K+, and Rb+) while ammonium and oxonium galloalunite decompose under formation of pure β-Ga2O3. The thermogravimetric results confirmed the analytical results on the galloalunites and thereby verified the stoichiometry of these synthetic products. Galloalunites with different monovalent cations in A site (i.e. Na+, K+, Rb+, H3O+ and NH4+) crystallize in the rhombohedral space group R-3m (#166). The effects of substitution on the unit cell parameters are rationalized in terms of the structural arrangements in galloalunites. The unit cell parameter cStoichiometric end member galloalunites of the general formula AGa3(SO4)2(OH)6, with A = Na+, K+, Rb+, H3O+, and NH4+ have been synthesized under hydrothermal conditions. These galloalunites were characterized by chemical methods, thermal analysis (DSC, TG coupled with mass spectroscopy), and powder X-ray diffraction (XRD). The stages of thermal decomposition of sodium, potassium and rubidium galloalunite show a common decomposition mechanism forming β-Ga2O3 and A2SO4 (A = Na+, K+, and Rb+) while ammonium and oxonium galloalunite decompose under formation of pure β-Ga2O3. The thermogravimetric results confirmed the analytical results on the galloalunites and thereby verified the stoichiometry of these synthetic products. Galloalunites with different monovalent cations in A site (i.e. Na+, K+, Rb+, H3O+ and NH4+) crystallize in the rhombohedral space group R-3m (#166). The effects of substitution on the unit cell parameters are rationalized in terms of the structural arrangements in galloalunites. The unit cell parameter c increases with increasing effective ionic radii of the cation in the A site, whereas the parameter a changes to a much lesser degree.show moreshow less

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Metadaten
Author: Wolfram W. Rudolph, Peer SchmidtORCiD
URL:http://www.sciencedirect.com/science/article/pii/S0040603111002310
DOI:https://doi.org/10.1016/j.tca.2011.04.013
Title of the source (English):Thermochimica Acta
Document Type:Scientific journal article peer-reviewed
Language:English
Year of publication:2011
Tag:Galloalunites; Synthesis; Thermal analysis; Unit cell parameters; X-ray diffraction
Volume/Year:521
Issue number:1-2
First Page:112
Last Page:120
Faculty/Chair:Fakultät 2 Umwelt und Naturwissenschaften / FG Anorganische Chemie
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