Electronic structure calculations for LaNi5 and LaNi5H7: energetics and elastic properties
| Autor: | T. W. Capehart, Jan F. Herbst, Louis G. Hector |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Chemistry
Hydride Phonon Mechanical Engineering Enthalpy Metals and Alloys Thermodynamics Ionic bonding General Medicine Electronic structure Standard enthalpy of formation Metal Crystallography symbols.namesake Mechanics of Materials visual_art visual_art.visual_art_medium Materials Chemistry symbols Crystallite Elastic modulus Debye |
| Zdroj: | Journal of Alloys and Compounds. 353:74-85 |
| ISSN: | 0925-8388 |
| DOI: | 10.1016/s0925-8388(02)01324-5 |
| Popis: | Density functional calculations of the electronic structure and enthalpy of formation Δ H of LaNi 5 and LaNi 5 H 7 are reported. Single-crystal elastic constants and Voigt–Reuss–Hill polycrystalline moduli were calculated for both materials using a stress-based least-squares fitting methodology. We obtain Δ H (0 K)=−40 kJ/mol H 2 for the hydride at zero temperature. Incorporating a Debye estimate of the phonon contribution we find Δ H (298 K)∼−39 kJ/mol/H 2 , a value that compares favorably with experimental determinations of −32 to −35 kJ/mol/H 2 . Our results indicate that the H–Ni and H–La interactions in the hydride are primarily metallic with a small ionic component. The calculated elastic moduli are in excellent accord with single-crystal measurements on LaNi 5 and with available data for polycrystalline samples of the parent and hydride. |
| Databáze: | OpenAIRE |
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