SYNTHESIS AND STRUCTURE OF A NEW Ca URANYL OXIDE HYDRATE, Ca[(UO2)4O3(OH)4](H2O)2, AND ITS RELATIONSHIP TO BECQUERELITE
Bibliographic record
Abstract
A new Ca uranyl oxide hydrate, Ca[(UO2)4O3(OH)4](H2O)2, has been synthesized by hydrothermal reaction of a solution of 0.03 M UO3 with calcite crystals. Fifteen hydrothermal synthesis experiments at 140, 180 and 220°C, with starting solution pH in the range 2 to 6, resulted in Ca[(UO2)4O3(OH)4](H2O)2. The structure, space group P 1, a 8.0556(8), b 8.4214(8), c 10.958(1) A, α 78.878(2), β 87.922(2), γ 72.277(2)°, V 649.6(2) A3, Z = 2, has been solved and refined on the basis of F 2 for all unique data collected with monochromatic Mo K α X-radiation and a CCD-based detector to an agreement factor ( R 1) of 3.47%, calculated using 2523 unique observed reflections ( F o ≥ 4σ F ). The structure contains four symmetrically distinct U6+ cations, each of which is part of a nearly linear (UO2)2+ uranyl ion. Three of the uranyl ions are coordinated by five ligands arranged at the equatorial vertices of pentagonal bipyramids, and the other is coordinated by four ligands at the equatorial vertices of a square bipyramid. Polymerization of the uranyl polyhedra by the sharing of vertices and edges results in a novel sheet. The single unique Ca2+ cation is located in the interlayer, together with two H2O groups, one of which is bonded to the Ca2+ cation, whereas the other is held in the structure by hydrogen bonding only. The phase Ca[(UO2)4O3(OH)4](H2O)2 contains more Ca than becquerelite, Ca[(UO2)6O4(OH)6](H2O)8, and polymerization of Ca polyhedra occurs in the interlayer, whereas in becquerelite, the Ca polyhedra do not share polyhedron elements.
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How this classification was reachedexpand
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) | 0.001 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".