High-pressure phases of lithium borohydride LiBH<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>4</mml:mn></mml:msub></mml:math>: A first-principles study
Bibliographic record
Abstract
High-pressure phase transformations in LiBH${}_{4}$ were theoretically investigated using first-principles density functional methods. A series of pressure-induced structural transformations are predicted in LiBH${}_{4}$, as Pnma (phase II) \ensuremath{\rightarrow} $I$4${}_{1}$/acd (phase III) \ensuremath{\rightarrow} NaCl type (phase V) \ensuremath{\rightarrow} NiAs type (phase VI) \ensuremath{\rightarrow} polymeric forms. The calculated pressures for the II \ensuremath{\rightarrow} III transition and the III \ensuremath{\rightarrow} V transition are 0.9 and 27 GPa, respectively, and both agree very well with recent experimental observations. A B1-B8 transformation becomes more favored at higher pressure, and this results in a distorted NiAs structure of LiBH${}_{4}$. Denoted as phase VI, the distorted NiAs structure is the lowest enthalpy phase of LiBH${}_{4}$ above 60 GPa and confirmed to be dynamically stable by phonon calculations. The ionic character and band gap of the phase VI decreases with increasing pressure. At still higher pressures, the extended structures formed by polymeric BH${}_{4}$ layers intercalated by Li${}^{\ensuremath{\delta}+}$ cations may exist, and these represent the metallic forms of LiBH${}_{4}$.
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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) | 0.003 | 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".