Structural and Spectroscopic Studies on Mesoporous Tantalum Oxide–Sodium Fulleride Composites with Conducting Fulleride Columns in the Pores
Bibliographic record
Abstract
Abstract Mesoporous tantalum oxide–sodium fulleride composites were synthesized by solution impregnation and characterized by elemental analysis, X‐ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption–desorption, X‐ray electron photoelectron spectroscopy (XPS), superconducting quantum interference device (SQUID) magnetometry, variable‐temperature electron transport measurements, and solid‐state 13C and 23Na NMR spectroscopy. The room temperature conductivity pattern as a function of sodium reduction level displayed a minimum at n = 3.0 and a maximum at n = 4.5, where n is the formal charge on the fulleride. The variable‐temperature conductivity measurements demonstrated that the n = 0.5 and n = 4.5 materials were semiconductors. Solid‐state 23Na NMR spectroscopy of the n = 0.5 composite exhibited three Na environments in the composites: two associated with the tantalum oxide walls and a third associated with the fulleride. The n = 3.0 and n = 4.5 materials showed a large build‐up of Na ions in the wall with no visible Na resonances associated with the fulleride, suggesting a structure in which the fulleride units exist as naked anions in one‐dimensional chains surrounded first by a layer of Na ions and then by a layer of mesoporous tantalum oxide. Solid‐state 13C NMR experiments showed more than one fulleride species in both the n = 0.5 and the n = 4.5 composites, as well as pure C60 in the n = 0.5 material, but almost exclusively C603– in the n = 3.0 material. The retention of carbon throughout reduction suggests that polymerization may have occurred, however this could not be verified by 13C NMR spectroscopy, because the region where sp3 fullerene resonances normally appear was obscured by solvent peaks.
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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".