High-Energy Density and Superhard Nitrogen-Rich B-N Compounds
Bibliographic record
Abstract
The pressure-induced transformation of diatomic nitrogen into nonmolecular polymeric phases may produce potentially useful high-energy-density materials. We combine first-principles calculations with structure searching to predict a new class of nitrogen-rich boron nitrides with a stoichiometry of ${\mathrm{B}}_{3}{\mathrm{N}}_{5}$ that are stable or metastable relative to solid ${\mathrm{N}}_{2}$ and $h$-BN at ambient pressure. The most stable phase at ambient pressure has a layered structure ($h{\text{\ensuremath{-}}\mathrm{B}}_{3}{\mathrm{N}}_{5}$) containing hexagonal ${\mathrm{B}}_{3}{\mathrm{N}}_{3}$ layers sandwiched with intercalated freely rotating ${\mathrm{N}}_{2}$ molecules. At 15 GPa, a three-dimensional $C22{2}_{1}$ structure with single N-N bonds becomes the most stable. This pressure is much lower than that required for triple-to-single bond transformation in pure solid nitrogen (110 GPa). More importantly, $C22{2}_{1}\text{\ensuremath{-}}{\mathrm{B}}_{3}{\mathrm{N}}_{5}$ is metastable, and can be recovered under ambient conditions. Its energy density of $\ensuremath{\sim}3.44\text{ }\text{ }\mathrm{kJ}/\mathrm{g}$ makes it a potential high-energy-density material. In addition, stress-strain calculations estimate a Vicker's hardness of $\ensuremath{\sim}44\text{ }\text{ }\mathrm{GPa}$. Structure searching reveals a new clathrate sodalitelike BN structure that is metastable under ambient conditions.
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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) | 0.000 | 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) | 0.000 | 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".