Stabilization of the Polar 0D Cs<sub>4</sub>Nb<sub>2–</sub><i><sub><i>x</i></sub></i>Ta<i><sub><i>x</i></sub></i>S<sub>11</sub> with Phase-Matched Second-Harmonic Generation and High Laser-Induced Damage Threshold
Bibliographic record
Abstract
The polysulfide compounds A 4 M 2 S 11 (A = K, Rb, Cs; M = Nb, Ta) are a class of 0D noncentrosymmetric compounds made up of molecular anionic clusters and crystallize in the polar space group Pca 2 1 . The clusters in these materials feature pentagonal bipyramidal dimeric units with the descriptive formula [M V 2 (S 2 ) 4 S 3 ] 4– . Differential thermal analysis and variable-temperature PXRD (VT-PXRD) show that the Ta-based materials melt incongruently, transforming to ATaS 3, while the Nb-based materials melt congruently. Additionally, the Nb-based materials have been shown to partially incorporate oxide ions in the presence of Nb x O y impurities to form A 4 Nb 2 S 10.7 O 0.3, which is made of molecular units with the formula [Nb 2 (S 2 ) 4 S 2.7 O 0.3 ] 4–, while the Ta-based materials do not form an oxychalcogenide. Upon alloying the two metals in a 1.75:0.25 Nb to Ta ratio, Cs 4 Nb 1.75 Ta 0.25 S 11, the compound now melts congruently and is resistant to partial oxygen substitution. Second-harmonic generation was studied on Cs 4 Nb 2 S 11, Cs 4 Ta 2 S 11, and Cs 4 Nb 1.75 Ta 0.25 S 11, showing exceptional laser-induced damage threshold (LIDT) at 1064 nm for all materials with the LIDT of Cs 4 Nb 1.75 Ta 0.25 S 11 being 0.475 GW/cm 2, 3 times that of the reported industry standard AgGaSe 2 . Additionally, phase matchability was observed at the mid-infrared wavelength of 3000 nm for Cs 4 Nb 2 S 11 and Cs 4 Nb 1.75 Ta 0.25 S 11 .
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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) | 0.002 | 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".