Ab initio calculations of MgH sub(2, MgH) sub(2):Ti and MgH sub(2:Co compounds)

• Published in: International journal of hydrogen energy 2010-01, Vol.35 (2), p.598-608
• Main Authors: Novakovic, Nikola, Novakovic, Jasmina Grbovic, Matovic, Ljiljana, Manasijevic, Miodrag, Radisavljevic, Ivana, Mamula, Bojana Paskas, Ivanovic, Nenad
• Format: Article
• Language: English
• Subjects: Alloying; Alloying effects; Alloys; Bonding strength; Hydrogen storage; Magnesium; Magnesium base alloys; Mathematical analysis
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2009.11.003

The understanding of hydrogen bonding in magnesium and magnesium based alloys is an important step toward its prospective use. In the present study, a density functional theory (DFT) based, full-potential augmented plane waves method of calculation, extended with local orbitals (FP-APW+lo), was used to investigate the stability of MgH sub(2 and MgH) sub(2):TM (TM = Ti and Co) 10 wt % alloys and the influence of this alloying on hydrogen storage properties of MgH sub(2 compound. Effects of a possible spin polarisation induced in the system by transition metal (TM) ions were considered too. It has been found that TM-H bonding is stronger than the Mg-H bond, but at the same time it weakens other bonds in the second and third coordination around a TM atom, which leads to overall destabilization of the MgH) sub(2) compound. Due to a higher number of d-electrons, this effect is more pronounced for Co alloying, where in addition, the spin polarisation has a noticeable and stabilising influence on the compound structure.