Hydrogen insertion effects on the electronic structure of equiatomic MgNi traced by ab initio calculations
Language
en
Article de revue
This item was published in
Zeitschrift fur Naturforschung B. 2013, vol. 68, n° 1, p. 44-50
Verlag der Zeitschrift Fuer Naturforschung
English Abstract
For equiatomic MgNi which can be hydrogenated up to the composition MgNiH1.6 at an absorption/desorption temperature of 200 °C, the effects of hydrogen absorption are approached with the model structures MgNiH, MgNiH2 and ...Read more >
For equiatomic MgNi which can be hydrogenated up to the composition MgNiH1.6 at an absorption/desorption temperature of 200 °C, the effects of hydrogen absorption are approached with the model structures MgNiH, MgNiH2 and MgNiH3. From full geometry optimization and calculated cohesive energies obtained within DFT, the MgNiH2 composition close to the experimental limit is identified as most stable. Charge density analysis shows an increasingly covalent character of hydrogen: MgNiH (H−0.67) → MgNiH2 (H−0.63) → MgNiH3 (H−0.55). While Mg-Ni bonding prevails in MgNi and hydrogenated model phases, extra itinerant low-energy Ni states appear when hydrogen is introduced signaling Ni-H bonding which prevails over Mg-H as evidenced from total energy calculations and chemical bonding analyses.Read less <
English Keywords
Hydrogen
Equiatomic MgNi
Iono-covalent character
Bader charge
Chemical bonding
Origin
Hal imported