CRYSTAL CHEMISTRY AND TOPOLOGY OF TWO FLUX-GROWN YTTRIUM SILICATES, BaKYSi2O7 AND Cs3YSi8O19
Bibliographic record
Abstract
Two new yttrium silicates have been synthesized by a high-temperature flux-growth technique in air. The phase BaKYSi 2 O 7 is monoclinic, with space group P 2 1 / n , a 9.775(2), b 5.718(1), c 13.096(3) A, β 104.61(3)°, V 708.3(3) A 3 , and Z = 4; Cs 3 YSi 8 O 19 is orthorhombic, space group Pnma , with a 11.476(2), b 7.059(1), c 26.971(5) A, V 2184.9(6) A 3 , and Z = 4. The crystal structures were determined from single-crystal X-ray-diffraction data and refined to R 1( F ) = 2.0% (BaKYSi 2 O 7 ) and R 1( F ) = 2.9% (Cs 3 YSi 8 O 19 ). The phase BaKYSi 2 O 7 represents a novel structure-type, and a compound that may also occur in nature. It has a mixed tetrahedron–octahedron framework structure containing Si 2 O 7 groups and octahedrally coordinated Y atoms ( = 2.256 A). Voids in the framework host [9]-coordinated Ba atoms and [8]-coordinated K atoms. The YO 6 octahedron shares each of its apices with oxygen atoms of the Si 2 O 7 groups. The unusually small Si–O–Si angle of the disilicate group [124.51(9)°] is noteworthy. The diphosphates Na 2 CaP 2 O 7 , M 2 SrP 2 O 7 ( M = K, Rb, Cs) and K 2 CdP 2 O 7 , and the diarsenate K 2 CaAs 2 O 7 , have closely related structures. The phase Cs 3 YSi 8 O 19 is isotypic with isoelectronic Cs 3 ScSi 8 O 19 and the second representative of the microporous framework structure-type MCV–1. The silicate has a mixed octahedron–tetrahedron framework structure with a [ T O 4 ]:[ M O 6 ] ratio of 8:1. The structure contains isolated YO 6 octahedra ( = 2.251 A) sharing corners with SiO 4 tetrahedra to form an open framework with four-, six- and eight-membered rings. Large voids host two fully occupied Cs positions and four partly occupied and disordered Cs positions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 source (direct Gemma or distilled Codex), 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".