Controlling the Luminescence of Rare-Earth Chalcogenide Iodides <i>RE</i><sub>3</sub>(Ge<sub>1–<i>x</i></sub>Si<sub><i>x</i></sub>)<sub>2</sub>S<sub>8</sub>I (<i>RE</i> = La, Ce, and Pr) and Ce<sub>3</sub>Si<sub>2</sub>(S<sub>1–<i>y</i></sub>Se<sub><i>y</i></sub>)<sub>8</sub>I
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
The rare-earth chalcogenide iodides RE 3 (Ge 1– x Si x ) 2 S 8 I ( RE = La, Ce, and Pr) and Ce 3 Si 2 (S 1– y Se y ) 8 I were prepared by reactions of the elements at 900 °C. Phase-pure samples and complete solid solutions were obtained for all series, as determined by powder X-ray diffraction patterns, with the cell parameters evolving smoothly. They adopt the monoclinic La 3 Si 2 O 8 Cl-type structure (space group C 2/ c ), containing isolated tetrahedra centered by the tetrel atoms and separated by the RE and I atoms. Single-crystal X-ray diffraction studies indicate that substitution of Si for Ge atoms in RE 3 (Ge 1– x Si x ) 2 S 8 I leads to complete disorder of the tetrel atoms, whereas partial substitution of Se for S atoms in Ce 3 Si 2 (S 1– y Se y ) 8 I occurs with preferential occupation of Se atoms. The optical band gaps increase slightly upon substitution with Si in RE 3 (Ge 1– x Si x ) 2 S 8 I (or negligibly in the case of the Ce-containing series, remaining at 2.8 eV), and they decrease dramatically upon substitution with Se in Ce 3 Si 2 (S 1– y Se y ) 8 I, from 2.8 to 1.9 eV. These band gaps are direct according to electronic structure calculations. The strong blue photoluminescence emission in Ce 3 Si 2 S 8 I shifts slightly to blue-green in Ce 3 (Ge 0.25 Si 0.75 ) 2 S 8 I and significantly to green in Ce 3 Si 2 (S 0.81 Se 0.19 ) 8 I, as quantified by their chromaticity coordinates. Increasing the concentration of Ge or Se tends to decrease the photoluminescence intensity and lifetime. For Ce 3 Si 2 S 8 I, the activation energy for thermal quenching is 0.68 eV.
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.
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 | 0.013 | 0.005 |
| Meta-epidemiology (narrow) | 0.011 | 0.011 |
| Meta-epidemiology (broad) | 0.013 | 0.004 |
| Bibliometrics | 0.002 | 0.006 |
| Science and technology studies | 0.006 | 0.010 |
| Scholarly communication | 0.006 | 0.005 |
| Open science | 0.009 | 0.007 |
| Research integrity | 0.007 | 0.006 |
| Insufficient payload (model declined to judge) | 0.000 | 0.001 |
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