2002/10/08 by Ponniah Vajeeston, P. Vajeeston, P. Ravindran +3 · 2 citations
Materials Science · Physics and Astronomy · #Advanced Chemical Physics Studies #Hydrogen Storage and Materials #Superconductivity in MgB2 and Alloys #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevlett.89.175506
published as Phys. Rev. Lett. 89, 175506 (2002) · 4 pages, 4 figures
openalex publication_date 2002/10/08 · arxiv created 2002/10/21 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The stability of MgH2 has been studied up to 20 GPa using density-functional total-energy calculations. At ambient pressure \ensuremathα\mathrm\text\ensuremath-MgH2 takes a TiO2-rutile-type structure. \ensuremathα\mathrm\text\ensuremath-MgH2 is predicted to transform into \ensuremathγ\mathrm\text\ensuremath-MgH2 at 0.39 GPa. The calculated structural data for \ensuremathα- and \ensuremathγ\mathrm\text\ensuremath-MgH2 are in very good agreement with experimental values. At equilibrium the energy difference between these modifications is very small, and as a result both phases coexist in a certain volume and pressure field. Above 3.84 GPa \ensuremathγ\mathrm\text\ensuremath-MgH2 transforms into \ensuremathβ\mathrm\text\ensuremath-MgH2, consistent with experimental findings. Two further transformations have been identified at still higher pressure: (i) \ensuremathβ- to \ensuremathδ\mathrm\text\ensuremath-MgH2 at 6.73 GPa and (ii) \ensuremathδ- to ϵ\mathrm\text\ensuremath-MgH2 at 10.26 GPa.