Low dimensionality materials: Origin of the reduced dimensonality in tin(ii) fluoridecontaining compounds and its study by X-Ray diffraction and Mössbauer spectroscopy
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Bibliographic record
Abstract
Isotropic materials have the same properties in all directions of space, with the same magnitude. Strict isotropy requires a spherical symmetry, hence a cubic unit-cell. All other crystal systems give rise to property anisotropy, i.e. direction dependence of properties and of their magnitude, although the anisotropy may often be weak enough to be quite insignificant. However, some materials show very strong anisotropy, owing to their layered structure, which is the result of unequal bond strength versus direction in space. Property anisotropy is usually the consequence of bonding anisotropy that gives anisotropic crystal growth, i.e. the crystals grow faster in some directions and slower in others, resulting in a crystallite shape that is often sheet-like (two-dimensional) or needle-like (one-dimensional). Many tin(II)-containing materials are found to have very strong low dimensionality: (1) SnF 2 /MCl (M = alkali metals and NH 4 ) give needle shaped crystals even long hair-shaped. For example, in M 3 Sn 5 Cl 3 F 10 , the intersection of planes of lone pairs creates cleavage planes in two directions, giving needle shaped crystals. Extreme cases of two-dimensionality were observed in MSnF 4 , particularly in -PbSnF 4 . Bonding anisotropy in tin(II)-containing materials is due to the tin stereoactive lone pair, when the lone pairs cluster in sheets, since no bonding to tin can take place in the lone pair direction. This gives rise to high preferred orientation of polycrystalline samples. The presentation will show how the anisotropy of the tin(II) quadrupole doublet, measured on polycrystalline samples subjected to an extremely enhanced preferred orientation, can be used to predict the direction of the lone pairs in the unit-cell and this, in turn, explain the direction of the cleavage planes. The presentation will focus on the use of X-ray diffraction and Mssbauer spectroscopy to characterize highly anisotropic phases and understand their structure-textural properties.
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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 | 0.003 | 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 | 0.001 |
| 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 it