THE STEREOCHEMISTRY AND CHEMICAL COMPOSITION OF INTERSTITIAL COMPLEXES IN URANYL-OXYSALT MINERALS
- 1 April 2008
- journal article
- review article
- Published by Mineralogical Association of Canada in The Canadian Mineralogist
- Vol. 46 (2), 467-501
- https://doi.org/10.3749/canmin.46.2.467
Abstract
The crystal structures and chemical compositions of uranyl-oxysalt minerals (primarily with sheet structural units) are interpreted in terms of the binary representation - bond-valence approach to the structure and chemistry of oxysalts. There is a coherent relation between the average basicity of the structural unit and [CNin], the average number of bonds to oxygen atoms of the structural unit from the interstitial complex and adjacent structural units. This relation allows calculation of the range of Lewis basicity for specific Structural units. The Lewis acidity of all interstitial complex is expressed graphically as a function of the amounts and coordination numbers of monovalent, divalent and trivalent interstitial cations and the amount of interstitial transformer (H2O) groups. The range in Lewis basicity for a specific structural unit may also be expressed graphically, and where there is overlap of the Lewis acidity and Lewis basicity, the valence-matching principle is satisfied, and the details of the possible interstitial complexes call be derived. There are three distinct types of interstitial (H2O) groups: transformer, non-transformer and inverse-transformer. Inverse-transformer (H2O) groups accept three bonds from cations, other (H2O) groups and (OH) groups of the structural unit. Their occurrence is rare and is limited to minerals with low bond-valence distribution factors. Detailed predictions of the number of transformer, non-transformer and inverse-transformer (H2O) groups in the minerals of the meta-autunite, uranophane, phosphuranylite, carnotite, zippeite and uranyl-hydroxy-hydrate groups (and synthetic analogues) are in good agreement with the observed chemical compositions.Keywords
This publication has 19 references indexed in Scilit:
- The crystal structure determinations and refinements of K2S2O7, KNaS2O7 and Na2S2O7 from X-ray powder and single crystal diffraction dataJournal of Solid State Chemistry, 2005
- Structures and synthesis of framework Rb and Cs uranyl arsenates and their relationships with their phosphate analoguesJournal of Solid State Chemistry, 2003
- The structure of hügelite, an arsenate of the phosphuranylite group, and its relationship to dumontiteMineralogical Magazine, 2003
- Expanding the Remarkable Structural Diversity of Uranyl Tellurites: Hydrothermal Preparation and Structures of K[UO2Te2O5(OH)], Tl3{(UO2)2[Te2O5(OH)](Te2O6)}·2H2O, β-Tl2[UO2(TeO3)2], and Sr3[UO2(TeO3)2](TeO3)2Inorganic Chemistry, 2002
- Mixed-Metal Uranium(VI) Iodates: Hydrothermal Syntheses, Structures, and Reactivity of Rb[UO2(CrO4)(IO3)(H2O)], A2[UO2(CrO4)(IO3)2] (A = K, Rb, Cs), and K2[UO2(MoO4)(IO3)2]Inorganic Chemistry, 2002
- Hydrothermal Syntheses, Structures, and Properties of the New Uranyl Selenites Ag2(UO2)(SeO3)2, M[(UO2)(HSeO3)(SeO3)] (M = K, Rb, Cs, Tl), and Pb(UO2)(SeO3)2Inorganic Chemistry, 2002
- A Novel Uranyl Sulfate Cluster in the Structure of Na6(UO2)(SO4)4(H2O)2Journal of Solid State Chemistry, 2002
- The Crystal Structure of Triuranyl Diphosphate TetrahydrateJournal of Solid State Chemistry, 2002
- Syntheses and Crystal Structures of Two Topologically Related Modifications of Cs2[(UO2)2(MoO4)3]Inorganic Chemistry, 2001
- Excision of Uranium Oxide Chains and Ribbons in the Novel One-Dimensional Uranyl Iodates K2[(UO2)3(IO3)4O2] and Ba[(UO2)2(IO3)2O2](H2O)Inorganic Chemistry, 2001