Comprehensive Band Gap and Electronic Structure Investigations of the Prominent Phosphors M<sub>2</sub>Si<sub>5</sub>N<sub>8</sub>:Eu<sup>2+</sup> (M = Ca, Sr, Ba) Determined Using Soft X-ray Spectroscopy and Density Functional Theory
Bibliographic record
Abstract
The suite of LED phosphors M2Si5N8:Eu2+ (M = Ca, Sr, Ba) emerged as indispensable solid-state light sources for the next-generation lighting industry and display systems due to their unique properties. As such, the structure–property relations underpinning their electronic structures are of prime interest. Their band gaps, electronic structures, optical properties, and energy levels are studied with a combination of soft X-ray spectroscopy and density functional theory (DFT) calculations. A clear trend is found where the tunable band gaps range from 3.70 ± 0.20 to 5.00 ± 0.20 eV (when going from Ba to Sr to Ca), following the predictions of the bonding model. The measurements and calculations are also used to derive a systematic trend between the measured band gaps of M2Si5N8 and are confirmed by our density functional theory calculations employing different exchange correlation functionals. These investigations present a comprehensive picture of the M2Si5N8 system, underlining their broad applicability and importance as one of the preeminent phosphors for LED lighting.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".