Structure and transport properties in the pseudo-binary phase system Li4SiS4 – Li4SnS4
Bibliographic record
Abstract
Thio-lithium superionic conductors (thio-LISICONs) are a family of promising solid electrolyte materials for potential applications in solid-state batteries. The orthorhombic polymorph of the thio-LISICON Li4SiS4 (o-Li4SiS4) has been known for decades, but its complete crystal structure has been reported only recently. Here, using single crystal X-ray diffraction we reevaluated the crystal structure of o-Li4SiS4 and show that o-Li4SiS4 crystallizes in space group Pmn21 (No. 31, a = 7.7694(15) Å, b = 13.731(3) Å, c = 6.1413(12) Å). The crystal structure of o-Li4SiS4 consists of isolated SiS4 tetrahedra arranged in a zig-zag-type manner, whereas Li atoms are coordinated both tetrahedrally and octahedrally by sulfur atoms of the SiS4 groups. Structures identified by first-principles calculations support the lower symmetry solution presented here, with the Pmn21 polymorph being more stable at room temperature than a higher symmetry phase. By knowing the accurate crystal structure of o-Li4SiS4 we investigated the solid solution behavior with another group IV thio-LISICON, Li4SnS4. Rietveld refinements of powder X-ray diffraction data revealed the solid solution Li4Si1-xSnxS4 (0 ≤ x ≤ 1, Δx = 0.1), which shows a nearly ideal Vegard-type behavior for all silicon-containing samples. 29Si and 119Sn magic-angle-spinning solid-state NMR and Raman spectroscopy showed the presence of SiS4 and SnS4 tetrahedra moieties, with the spectra showing expected behavior consistent with the silicon-tin ratio in the materials. Electrochemical impedance spectroscopy revealed the highest ionic conductivity of 8.4×10-6 S cm-1 at 25 °C for Li4Si0.5Sn0.5S4, accompanied by the lowest migration barrier of ~0.37 eV.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".