Effect of Yb<sup>3+</sup> Codoping on the Upconversion Emission in Nanocrystalline Y<sub>2</sub>O<sub>3</sub>:Er<sup>3+</sup>
Bibliographic record
Abstract
The Stokes emission of nanocrystalline and bulk Y 2 O 3:Er 3+, Yb 3+ following 488 nm were reported. Two nanocrystalline samples were studied, one produced via propellant synthesis and the other via wet synthesis. Green, red, and NIR emission from the Er 3+ ion was observed in both bulk and nanocrystalline samples. Emission from the 2 F 5/2 → 2 F 7/2 Yb 3+ transition was also observed in the bulk and nanocrystalline samples following 488 nm excitation, thereby signifying the presence of an energy transfer process from Er 3+ to Yb 3+ . The peaks attributed to Yb 3+ emission were much less intense in the nanocrystalline material, indicating that the energy transfer process occurs less readily in this material because of the inherent high phonon energies from the adsorbed CO 2 and H 2 O on their surface. Following excitation with 978 nm, green and red anti-Stokes luminescence was evidenced in the samples under investigation. An enhancement of the red emission is observed in both bulk and nanocrystalline samples, although to a much greater degree in nanocrystalline Y 2 O 3:Er 3+, Yb 3+ . The enhancement of the red emission was shown to occur due to an ion-pair process of the form: ( 4 F 7/2, 4 I 11/2 ) → ( 4 F 9/2, 4 F 9/2 ), which directly populates the 4 F 9/2 state. However, this process cannot account for the drastic difference in the magnitude of the red enhancement between bulk and nanocrystalline samples. A phonon-assisted energy transfer process was found to be operative, which also populates the 4 F 9/2 state. This process occurs more readily in the nanocrystalline material as the large vibrational quanta from the adsorbed carbonate and hydroxyl ions can easily bridge the mismatch in energy.
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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".