| DOI | Trouver le DOI : https://doi.org/10.1063/1.1705573 |
|---|
| Auteur | Rechercher : Velardez, Gustavo; Rechercher : Alavi, Saman; Rechercher : Thompson, Donald |
|---|
| Format | Texte, Article |
|---|
| Sujet | ammonium compounds; diffusion; melting point; molecular dynamics method; molecular reorientation; solid-liquid transformations; solid-state phase transformations; viscosity; voids (solid) |
|---|
| Résumé | Molecular dynamics simulations are used to calculate the melting point and some aspects of high-temperature solid-state phase transitions of ammonium nitrate (AN). The force field used in the simulations is that developed by Sorescu and Thompson [J. Phys. Chem. A 105, 720 (2001)] to describe the solid-state properties of the low-temperature phase-V AN. Simulations at various temperatures were performed with this force field for a 4�4�5 supercell of phase-II AN. The melting point of AN was determined from calculations on this supercell with voids introduced in the solid structure to eliminate superheating effects. The melting temperature was determined by calculating the density and the nitrogen�nitrogen radial distribution functions as functions of temperature. The melting point was predicted to be in the range 445�10 K, in excellent agreement with the experimental value of 442 K. The computed temperature dependences of the density, diffusion, and viscosity coefficient for the liquid are in good agreement with experiment. Structural changes in the perfect crystal at various temperatures were also investigated. The ammonium ions in the phase-II structure are rotationally disordered at 400 K. At higher temperatures, beginning at 530 K, the nitrate ions are essentially rotationally unhindered. The density and radial distribution functions in this temperature range show that the AN solid is superheated. The rotational disorder is qualitatively similar to that observed in the experimental phase-II to phase-I solid-state transition. |
|---|
| Date de publication | 2004-05-15 |
|---|
| Dans | |
|---|
| Langue | anglais |
|---|
| Publications évaluées par des pairs | Oui |
|---|
| Publication du CNRC | Cette publication n’est pas du CNRCCe sont des publications qui ont été rédigées par un auteur du CNRC, mais avant que celui-ci soit employé du CNRC. |
|---|
| Numéro NPARC | 12327832 |
|---|
| Exporter la notice | Exporter en format RIS |
|---|
| Signaler une correction | Signaler une correction (s'ouvre dans un nouvel onglet) |
|---|
| Identificateur de l’enregistrement | 1abf0a21-62ca-42be-870d-e4ddc5e1d613 |
|---|
| Enregistrement créé | 2009-09-10 |
|---|
| Enregistrement modifié | 2020-04-17 |
|---|
