Variable temperature<i>X</i>-band EPR of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Gd</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">LaNbO</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">PrNbO</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>crystals: Low-symmetry effect, influence of host and impurity paramagnetic ions on linewidth, and onset of antiferromagnetism
Bibliographic record
Abstract
EPR studies on ${\mathrm{Gd}}^{3+}$-doped diamagnetic ${\mathrm{LaNbO}}_{4}$ and paramagnetic ${\mathrm{PrNbO}}_{4}$ crystals containing ${\mathrm{Nd}}^{3+}$ and ${\mathrm{Ce}}^{3+}$ impurity Kramers ions were carried out at the X band (9.61 GHz) in the 4--295 K temperature range. The observed asymmetry in the extrema of ${\mathrm{Gd}}^{3+}$ EPR line positions in the angular variations of the EPR lines in the two hosts for the various transitions observed for the orientations of the external magnetic field about the Z and Y magnetic axes in the ac crystallographic plane was ascribed to the existence of the low, monoclinic site symmetry at the ${\mathrm{Gd}}^{3+}$ ion. The ${\mathrm{Gd}}^{3+}$ spin-Hamiltonian parameters were estimated from EPR line positions in the two crystals at 8, 73, and 295 K. The variation of the ${\mathrm{Gd}}^{3+}$ EPR linewidth as a function of temperature in the paramagnetic ${\mathrm{PrNbO}}_{4}$ host between 100 and 295 K is explained to be due to the dynamical dipolar and exchange interactions between the impurity ${\mathrm{Gd}}^{3+}$ ions and the host paramagnetic ${\mathrm{Pr}}^{3+}$ ions. The increase in the linewidth with decreasing temperature below 30 K in the two crystals implies the onset of antiferromagnetic ordering, consistent with ${T}_{c}=1.6$ and 2.4 K in ${\mathrm{LaNbO}}_{4}$ and ${\mathrm{PrNbO}}_{4}$ crystals. The observed decrease in the integrated intensity of ${\mathrm{Gd}}^{3+}$ EPR signal with lowering temperature in the two crystals is ascribed to the coupling of ${\mathrm{Gd}}^{3+}$ ions to the impurity ${\mathrm{Nd}}^{3+}$ and ${\mathrm{Ce}}^{3+}$ Kramers ions present 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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.088 | 0.025 |
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".