Radiation-Induced Formation of Chromium Oxide Nanoparticles: Role of Radical Scavengers on the Redox Kinetics and Particle Size
Bibliographic record
Abstract
The formation of Cr 2 O 3 nanoparticles by γ-irradiation of dichromate solutions was investigated in the presence of radical scavengers, tert -butyl alcohol, nitrous oxide, and dissolved oxygen. The concentrations of Cr VI and Cr III species and the chemical composition and sizes of particles that were formed were measured as a function of irradiation time. A mechanism is proposed that is consistent with the observed effects of scavengers on the kinetics of reduction of Cr VI in solution to solid Cr III and the final size of Cr 2 O 3 nanoparticles that are formed. The chromium reduction occurs in three stages: Stage I involves homogeneous aqueous reduction of Cr VI (aq) to Cr III (aq) followed by spontaneous condensation of Cr(OH) 3, providing nucleation sites onto which Cr VI and Cr III coprecipitate and form mixed Cr VI /Cr III oxide/hydroxide particles. In Stage II, the aqueous reduction of Cr VI (aq) and Cr III (aq) reaches steady state but the adsorption of Cr VI continues, growing the mixed Cr VI /Cr III oxide/hydroxide particles. Stage 3 involves the solid-state conversion of Cr VI and Cr III, and the particles slowly convert from a mixed Cr VI /Cr III oxide/hydroxide to Cr(OH) 3 and then to Cr 2 O 3 . Adding a radical scavenger in solution affects the kinetics of particle formation and growth at different stages differently. This information can be used to tailor the final sizes of particles.
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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 | 0.001 |
| 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 | 0.001 | 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".