Geikielite–ecandrewsite solid solutions: synthesis and crystal structures of the Mg<sub>1−<i>x</i> </sub>Zn<sub> <i>x</i> </sub>TiO<sub>3</sub> (0 ≤ <i>x</i> ≤ 0.8) series
Bibliographic record
Abstract
The crystal structures of members of the geikielite–ecandrewsite solid solution series, Mg1 − x Zn x TiO3 (0 ≤ x ≤ 0.8 a.p.f.u. Zn; a.p.f.u. = atoms per formula unit), synthesized by ceramic methods in air at ambient pressure, have been characterized by Rietveld analysis of X-ray powder diffraction patterns. These synthetic titanates adopt an ordered R\overline 3 structure similar to that of ilmenite. The maximum solubility of Zn in MgTiO3 is considered to be ∼ 0.8 a.p.f.u. Zn, as compounds with greater Zn content could not be synthesized at ambient conditions. Data are given for the cell dimensions and atomic coordinates, together with bond lengths, volumes and distortion indices for all the coordination polyhedra. Within the solid-solution series unit-cell parameters and unit-cell volumes increase with Zn content. All compounds consist of distorted (Mg,Zn)O6 and TiO6 polyhedra and, in common with geikielite and ilmenite (sensu lato), TiO6 polyhedra are distorted to a greater extent than (Mg,Zn)O6. The displacements of (Mg,Zn) and Ti from the centers of their coordination polyhedra vary insignificantly with increasing Zn content. The interlayer distance across the vacant octahedral site in the TiO6 layer decreases slightly with the entry of the larger Zn2+ cation into the vi A site. The empirically obtained upper limit of the Goldschmidt tolerance factor (t) for A 2+ BO3 compounds adopting an ordered R\overline 3 structure is 0.755. The absence of natural solid solutions between geikielite and ecandrewsite seems to be due to the contrasting geochemistry of Mg and Zn rather than for crystallochemical reasons.
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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".