SYNTHESIS AND CRYSTAL STRUCTURE OF A NEW Pb URANYL OXIDE HYDRATE WITH A FRAMEWORK STRUCTURE THAT CONTAINS CHANNELS
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Bibliographic record
Abstract
Using lead oxide, uranyl nitrate and ultrapure water, seven hydrothermal synthesis experiments were performed with Pb:U molar ratios ranging from 1:1 to 1:10. Reaction products were characterized by powder and single-crystal X-ray diffraction. Two novel Pb uranyl oxide hydrates were found, with structural formulae Pb2(H2O)[(UO2)10UO12(OH)6(H2O)2] and Pb0.5[(UO2)4O2(OH)5](H2O)4 (Pb-poor fourmarierite). The synthesis products are related to the Pb:U molar ratio of the solution, and indicate a trend from curite, Pb3+x(H2O)2[(UO2)4O4+x(OH)3–x]2, to Pb2(H2O)[(UO2)10UO12(OH)6(H2O)2], then to Pb0.5[(UO2)4O2(OH)5](H2O)4 with decreasing Pb in the solution. The structure of Pb2(H2O)[(UO2)10UO12(OH)6(H2O)2], Z = 4, monoclinic, space group C2/c, a 13.281(5), b 10.223(4), c 26.10(1) Å, 103.202(6)°, V 3450(2) Å3, was solved by direct methods and refined on the basis of F2 using 4065 unique reflections. The agreement index (R1) was 6.38%, calculated for 1306 unique observed reflections (|Fo | ≥ 4F). The structure contains complex chains of edge- and vertex-sharing uranyl pentagonal and square bipyramids, as well as distorted U6+O6 octahedra, along both the [110] and [¯110] directions. The chains in the two orientations are linked at z ≈ 0.25 and z ≈ 0.75, forming a framework that contains elongate open channels. The Pb2+ cations occur in the channels between adjacent chains.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it