Phosphorescence in Mn<sup>4+</sup>-Doped<i>R</i><sup>+</sup>/<i>R</i><sup>2+</sup>Germanates (<i>R</i><sup>+</sup>= Na<sup>+</sup>or K<sup>+</sup>,<i>R</i><sup>2+</sup>= Sr<sup>2+</sup>)
Bibliographic record
Abstract
Single crystals of three new compounds, Na 0.36 Sr 0.82 Ge 4 O 9 ( 1, proposed composition), Na 2 SrGe 6 O 14 ( 2 ), and K 2 SrGe 8 O 18 ( 3 ), were obtained and characterized using single-crystal X-ray diffraction. Their structures contain three-dimensional (3D) anionic frameworks built from GeO 4 and GeO 6 polyhedra. The presence of octahedral Ge 4+ sites makes the new phases suitable for Mn 4+ substitution to obtain red-emitting phosphors with a potential application for light conversion. Photoluminescence properties of Mn 4+ -substituted Na 2 SrGe 6 O 14 ( 2 ) and K 2 SrGe 8 O 18 ( 3 ) samples were studied over a range of temperatures, and red light photoluminescence associated with the electronic transitions of tetravalent manganese was observed. The Na 2 SrGe 6 O 14 ( 2 ) phase was also substituted with Pr 3+ on the mixed Na–Sr site similar to the previously studied Na 2 CaGe 6 O 14:Pr 3+ . The red emission peak of the Pr 3+ activator occurs at a shorter wavelength (610 nm) compared to that of Mn 4+ (662–663 nm). Additionally, second harmonic generation (SHG) data were collected for the noncentrosymmetric Na 2 SrGe 6 O 14 ( 2 ) phase, indicating weak SHG activity. Diffuse reflectance spectroscopy and density of states calculations were performed to estimate the band gap values for pristine Na 2 SrGe 6 O 14 ( 2 ) and K 2 SrGe 8 O 18 ( 3 ) phases.
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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".