A NEW RARE-EARTH-ELEMENT URANYL CARBONATE SHEET IN THE STRUCTURE OF BIJVOETITE-(Y)
Bibliographic record
Abstract
The crystal structure of bijvoetite-(Y), [M83+(H2O)25(UO2)16O8(OH)8(CO3)16](H2O)14, M = (Y, REE), pseudo-orthorhombic, monoclinic, a 21.234(3), b 12.958(2), c 44.911(6) Å, b 90.00(2)°, V 12,357(6) Å3, space group B1211, Z = 4, was solved by direct methods and refined by least-squares techniques to an agreement index (R) of 8.4 % and a goodness of fit (S) of 0.81 for 6622 unique observed (|Fo |> 4sF) reflections collected for a twinned crystal using graphite-monochromatic MoKa X-radiation and a CCD area detector. There are 16 symmetrically independent U6+ positions, each of which is part of near-linear (U6+O2)2+ uranyl ion. Eight uranyl ions are coordinated by three O2 – and two (OH) – anions each, resulting in uranyl pentagonal bipyramids, and eight uranyl ions are coordinated by six O2 – anions each, forming uranyl hexagonal bipyramids. The structure contains 16 unique carbonate groups and eight unique M3+ sites that are occupied by variable amounts of Y, Dy and other REEs. The structure of bijvoetite-(Y) is based on a novel uranyl carbonate chain that is parallel to [100], involving edge-sharing dimers of uranyl pen-tagonal bipyramids, edge-sharing dimers of uranyl hexagonal bipyramids, and carbonate groups. The chains are cross-linked by irregular M3+fn (f: unspecified ligand) polyhedra, forming (Y,REE)-bearing uranyl carbonate sheets that are parallel to (010). The sheet in bijvoetite-(Y) is based upon a new sheet anion-topology. There are 39 symmetrically unique H2O groups in the structure, 25 of which are bonded to M3+ and 14 of which are located in the interlayer, where they are held in place by H bonds. The interlayer of the structure contains only H2O groups, and adjacent sheets are connected by H bonds only. The discovery of the
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.024 | 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".