Magnetic resonance studies of Co2+ ions in nanoparticles of SnO2 processed at different temperatures
Bibliographic record
Abstract
Cobalt doping (⩽1%) produces ferromagnetism at room temperature in semiconducting SnO2, presumably due to oxygen vacancies and/or changes in carrier concentration. Electron paramagnetic resonance (EPR) is a sensitive technique to investigate the Co ionic states and their local environments and/or interactions. This paper reports EPR studies of Co2+ ions doped in chemically synthesized nanoparticles of SnO2 carried out at 5K. EPR spectra were recorded from 600°C prepared SnO2 with Co concentrations of 0.5%, 1%, 3%, 5%, 8%, and 12% and from 1% Co-doped SnO2 prepared at temperatures of 150, 250, 350, 450, 600, and 830°C. Each EPR spectrum in samples with cobalt doping can be simulated as an overlap of spectra due to two broad ferromagnetic resonance lines and those due to interstitially and substitutionally incorporated Co2+ ions with effective spin S=1∕2 characterized by their particular g and A tensors. It is concluded that the Co2+ ions occupy substitutional as well as interstitial sites of SnO2 and that a fraction, albeit small, of the doped Co2+ spins contribute to the ordered ferromagnetic state. The relative concentrations of these different components depend on the annealing temperature and Co concentration of the samples.
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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".