Crystal, Magnetic Structures, and Bonding Interactions in the TiNiSi-Type Hydride CeMgSnH: Experimental and Computational Studies

• Published in: Chemistry of materials 2024-06, Vol.36 (12), p.6257-6268
• Main Authors: Yartys, Volodymyr A., Akselrud, Lev G., Denys, Roman V., Vajeeston, Ponniah, Ouladdiaf, Bachir, Dankelman, Robert, Plomp, Jeroen, Koldemir, Aylin, Schumacher, Lars, Kremer, Reinhard K., Pöttgen, Rainer, Wragg, David S., Eggert, Bruno Guilherme Fischer, Berezovets, Vasyl
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.4c01104

By combining experimental and computational studies, the orthorhombic stannide CeMgSn with a TiNiSi-type structure has been characterized as a potential hydrogen storage material. Experimental studies of the formed monohydride CeMgSnH including hydrogen absorption–desorption, thermal desorption spectroscopy, synchrotron and neutron powder diffraction (298 and 2 K), magnetization, and 119Sn Mössbauer spectroscopic measurements are discussed in parallel with ab initio electronic structure calculations. A small, 1.27 vol %, expansion of the unit cell of CeMgSn during its transformation into a thermally stable CeMgSnH monohydride is caused by an ordered insertion of H atoms into half of the available Ce3Mg tetrahedral interstices leaving the CeMg3 tetrahedra unoccupied. The bonding in CeMgSnH is dominated by strong Ce–Sn and Mg–Sn interactions which are almost not altered by hydrogenation, whereas the H atoms carry a small negative charge and show bonding interactions with Ce and Mg. Hydrogenation causes a conversion of the antiferromagnetic CeMgSn into ferromagnetic CeMgSnH with the Ce moments aligned along [001] with a magnetic moment of 1.4(3) μB. The 119Sn isomer shifts and the values of quadrupole splitting in the Mössbauer spectra suggest a similar s-electron density distribution for the Ce- and La-containing REMgSnH monohydrides.