- journal_title：The Canadian Mineralogist
- Contributor：Sergey V. Krivovichev ; Robert J. Finch ; Peter C. Burns
- Publisher：Mineralogical Association of Canada
- Date：2002-
- Format：text/html
- Language：en
- Identifier：10.2113/gscanmin.40.1.193
- journal_abbrev：Can Mineral
- issn：0008-4476
- volume：40
- issue：1
- firstpage：193
- section：Articles
Two alkali uranyl dimolybdates, Na2[(UO2)(MoO4)2] and K2[(UO2)(MoO4)2](H2O), have been synthesized by high-temperature solid-state reactions and hydrothermal methods, respectively. The structures of both compounds were solved by direct methods and refined on the basis of F2 for all unique data collected with monochromatic MoKα X-radiation and a CCD (charge-coupled device) detector. The structure of Na2[(UO2)(MoO4)2] was refined to an agreement factor (R1) of 3.1%, calculated from 2089 unique reflections (|Fo| ≥ 4σF); it is orthorhombic, space group P212121, a 7.2298(5), b 11.3240(8), c 12.0134(8) Å, V 983.5(1) Å3, Z = 4. The structure of K2[(UO2)(MoO4)2](H2O) was refined to an R1 of 3.7%, calculated from 2181 unique reflections (Fo ≥ 4σF); it is monoclinic, space group P21/c, a 7.893(2), b 10.907(2), c 13.558(3) Å, β 98.70(3)°, V 1153.8(4) Å3, Z = 4. Both structures are based upon sheets of uranyl pentagonal bipyramids and molybdate tetrahedra. The structural sheets in the two compounds are isochemical but topologically distinct.