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Structure and chemical bonding in MgNi2H3 from combined high resolution synchrotron and neutron diffraction studies and ab initio electronic structure calculationsстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 19 октября 2015 г.
- Авторы: Yartys V.A., Antonov V.E., Chernyshov D., Crivello J.C., Denys R.V., Fedotov V.K., Gupta M., Kulakov V.I., Latroche M., Sheptyakov D.
- Журнал: Acta Materialia
- Том: 98
- Год издания: 2015
- Издательство: Elsevier BV
- Местоположение издательства: Netherlands
- Первая страница: 416
- Последняя страница: 422
- DOI: 10.1016/j.actamat.2015.07.053
- Аннотация: Our earlier study [V.A. Yartys et al., Acta Mater. 82 (2015) 316] showed that at high hydrogen pressures, hexagonal MgNi2 undergoes a hydrogen assisted phase transition into the orthorhombic MoSi2-type structure. Here we report on a combined high resolution synchrotron and neutron diffraction investigation of the crystal structure of MgNi2D3, and ab initio modeling of its electronic structure that revealed the mechanism of the metal-hydrogen bonding. The diffraction data collected at 293 and 1.8 K are well described with a Cmca unit cell with H atoms filling positions of two types, inside the deformed octahedra Mg4Ni2 and in the infinite bended spirals -Ni-H-Ni-H- penetrating through the structure. DFT calculations showed that the Cmca structure of MgNi2D3 is the most stable one among all considered alternatives, both from the electronic structure and the lattice dynamic arguments. The Bader charge analysis for MgNi2H3 indicates an electronic transfer from Mg (-1.56 e-) to Ni (+0.21e-), H1 (+0.56e-) and H2 (+0.31e-). The phonon dispersion curves of MgNi2H3 all show positive frequencies, indicating that the structure is mechanically stable. The calculated gross heat of formation of the Cmca phase of MgNi2H3 is -37.3 kJ/mol-H2, which makes it by 3 kJ/mol-H2 more stable than the prototype structures tested in [V.A. Yartys et al., 2015]. The stability of the crystal structure of MgNi2H3 is enhanced by the formation of directional Ni-H covalent bonds supplemented by the electron transfer from Mg to both Ni and H atoms.
- Добавил в систему: Антонов Владимир Евгеньевич