TY - GEN A1 - Rudorf, Wolfram W. A1 - Schmidt, Peer T1 - Studies on synthetic galloalunites AGa3(SO4)2(OH)6: Synthesis, Thermal analysis, and X-ray characterization T2 - Thermochimica Acta N2 - 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 c increases with increasing effective ionic radii of the cation in the A site, whereas the parameter a changes to a much lesser degree. KW - Synthesis KW - Galloalunites KW - X-ray diffraction KW - Unit cell parameters KW - Thermal analysis Y1 - 2011 UR - http://www.sciencedirect.com/science/article/pii/S0040603111002310 U6 - https://doi.org/10.1016/j.tca.2011.04.013 VL - 521 IS - 1-2 SP - 112 EP - 120 ER -