SINGLE-CRYSTAL EPR STUDY OF Fe3+ AND VO2+ IN PREHNITE FROM THE JEFFREY MINE, ASBESTOS, QUEBEC
Bibliographic record
Abstract
Prehnite from the Jeffrey mine, in Asbestos, Quebec, has been investigated by optical microscopy, electron-microprobe analysis, single-crystal X-ray-diffraction (XRD) analysis, and electron paramagnetic resonance (EPR) spectroscopy. Electron-microprobe analyses yield an average iron content of 0.053(34) wt% Fe 2 O 3 ; single-crystal XRD intensity datasets confirm the space group P 2 cm . Single-crystal EPR spectra measured from 290 to 13 K reveal at least six paramagnetic defects: three Fe 3+ centers, a VO 2+ radical, a Mn 2+ center, and an Al-associated O − center. Spin-Hamiltonian parameters of the VO 2+ radical show that it resides at an octahedral site and most likely originated from a V 3+ O 4 (OH) 2 octahedron by removal of a proton and trapping of a hole to form a covalent V=O bond during natural radiation. Spin-Hamiltonian parameters, including the high-spin terms of type S 4 , BS 3 and BS 5 , for the dominant Fe 3+ center also show it to reside at an octahedral site. Two less abundant Fe 3+ centers have similar orientations in effective principal axes of g, indicative of occupancies at the octahedral site as well. Their differences in effective principal values of g may be attributed to different degrees of local distortion of the octahedral site. A previous interpretation of the powder EPR spectra for two Fe 3+ sites in prehnite has been shown to be incorrect. Spin-Hamiltonian parameters for Fe 3+ in prehnite have wide implications for interpretation of EPR spectra of Fe 3+ in layer silicates.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".