Synthesis and characterization of polyureasilazane derived SiCN ceramics
Bibliographic record
Abstract
Samples of SiCN ceramics were synthesized by thermal treatment of commercially available CERASET™ polyureasilazane, used as liquid-polymer precursor, at pyrolysis temperatures of 1000, 1050, 1100, 1150, and 1200°C. Electron paramagnetic resonance (EPR) signals due to sp2-hybridized carbon-related dangling bonds were recorded over the 4–300K temperature range at X band (9.6GHz), and the spectra showed the presence of an intense EPR line with g=2.0027 at room temperature for all samples; at liquid helium temperature an additional line was seen present as a shoulder to main line. These two signals are due to carbon-related dangling bonds present as (i) defects on the free-carbon phase and (ii) within the bulk of SiCN ceramic network. The value of the antiferromagnetic exchange constant between dangling bonds in the various samples, not hitherto available in the literature, was estimated from the temperature variation of the EPR linewidth to be anywhere from J=−12 to J=−15K in the samples synthesized at 1000, 1100, and 1150°C. The EPR linewidth of the samples decreased with increasing pyrolysis temperature of a sample, being 0.07mT at X band at room temperature for the samples synthesized at 1150 and 1200°C, which can be used potentially as stable g markers, due to their very narrow linewidth. The W-band (95GHz) room-temperature spectrum of the sample pyrolyzed at 1100°C exhibited only one line consistent with the X-band spectrum. At higher frequency of G band (170GHz) the EPR spectra are better resolved, clearly showing the presence of a strong (g=2.0027) and a weak (g=2.0032) EPR line at room temperature, and the latter corresponds to the line present at X band as shoulder at liquid-helium temperature. In addition, nuclear magnetic resonance measurements were carried out to confirm the existence of free-carbon phase and oxygen atoms in 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".