In situ High-Pressure Studies of Energetic Materials by Vibrational Spectroscopy and X-ray diffraction
Notice bibliographique
Résumé
Nitrogen-rich materials have been considered as the most promising replacement of traditional energetic materials due to the large energy gap between the different nitrogen allotropes as well as the generation of environmental friendly nitrogen gas as the end-product. As a result, methods of synthesizing the nitrogen-rich materials have received increasing attention. Apart from the traditional chemical synthesis, high-pressure technique had been proved an effective tool to create such kinds of materials. However, several issues still existed concerning the high-pressure synthesis of energetic materials. Therefore, searching for precursors is of great interest. Here we report studies of four promising precursors, 5-aminotetrazole, 5-methyltetrazole, 5, 5´-bis(2-methyltetrazolyl)amine monohydrate and cyanuric triazide, under high pressure by Raman and IR spectroscopy, among which 5, 5´-bis(2-methyltetrazolyl)amine monohydrate and cyanuric triazide were also studied using X-ray diffraction. Besides, the high-pressure behavior of s-triazine was also investigated to have an in-depth understanding of the properties of cyanuric triazide.\nIn chapter 2, 5-aminotetrazole and 5-methyltetrazole were investigated and compared to examine the pressure effects on the ring structures and the high-pressure behaviors. No phase transitions for 5-aminotetrazole were found in the whole pressure range. However, four phase transitions were observed for 5-methyltetrazole, evidenced by the by the appearance of new lattice modes, the changes in peak profile as well as the pressure dependence of Raman lattice modes over different pressure ranges. Upon decompression, the tetrazole ring vibration modes in both compounds were fully recovered, suggesting the high stability of the tetrazole ring. The Raman and IR spectroscopic data together allowed for the analysis of the possible reasons of the stability of the tetrazole ring.\nIn chapter 3, another tetrazole derivative, 5, 5´-bis(2-methyltetrazolyl)amine monohydrate, was investigated by vibrational spectroscopy and X-ray diffraction. The Raman and IR spectroscopic data together with the XRD patterns collectively suggested there were no phase transitions in the entire investigated pressure range. Several changes were observed during compression and possible mechanisms were proposed. Upon decompression, all the Raman and IR modes were completely recovered, indicating the reversibility and good stability of this material.\nChapter 4 focuses on the high-pressure studies of two six-member aromatic rings, s-triazine and cyanuric triazide. A total of four phase transitions for s-triazine were observed, evidenced by changes in peak profile, the number of vibrational modes, as well as the pressure dependence of Raman lattice modes over different pressure ranges. The transition was identified irreversible for the lattice modes were not recovered upon decompression. In addition, a ring-opening reaction took place, suggested by the recovered Raman and IR internal modes. For cyanuric triazide, no phase transitions were observed in the pressure range of 0-26 GPa and one chemical reaction above 26 GPa. In addition, the transition was partially irreversible evidenced by the different Raman profiles in different parts of the sample. Possible reaction mechanisms were proposed accordingly.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».