Two Ce(SO4)2·4H2O polymorphs: Crystal structure and thermal behavior |
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| Authors: | Barbara M Casari Vratislav Langer |
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| Institution: | a Department of Chemistry, Inorganic Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden
b Environmental Inorganic Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden |
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| Abstract: | Syntheses, crystal structures and thermal behavior of two polymorphic forms of Ce(SO4)2·4H2O are reported. The first modification, α-Ce(SO4)2·4H2O (I), crystallizes in the orthorhombic space group Fddd, with a=5.6587(1), b=12.0469(2), c=26.7201(3) Å and Z=8. The second modification, β-Ce(SO4)2·4H2O (II), crystallizes in the orthorhombic space group Pnma, with a=14.6019(2), b=11.0546(2), c=5.6340(1) Å and Z=4. In both structures, the cerium atoms have eight ligands: four water molecules and four sulfate groups. The mutual position of the ligands differs in (I) and (II), resulting in geometrical isomerism. Both these structures are built up by layers of Ce(H2O)4(SO4)2 held together by a hydrogen bonding network. The dehydration of Ce(SO4)2·4H2O is a two step (I) and one step (II) process, respectively, forming Ce(SO4)2 in both cases. During the decomposition of the anhydrous form, Ce(SO4)2, into the final product CeO2, intermediate xCeO2·yCe(SO4)2 species are formed. |
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| Keywords: | Ce(SO4)2· 4H2O Tetrahydrated ceric sulfate Cerium sulfate Sulfate decomposition Thermogravimetry Differential scanning calorimetry X-ray diffraction |
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