In Situ Hydrogenation of the Zintl Phase SrGe

Henry Auer; Dirk Wallacher; Thomas Christian Hansen; Holger Kohlmann

doi:10.1021/acs.inorgchem.6b01945

In Situ Hydrogenation of the Zintl Phase SrGe

Inorg Chem. 2017 Feb 6;56(3):1072-1079. doi: 10.1021/acs.inorgchem.6b01945. Epub 2017 Jan 18.

Authors

Henry Auer¹, Dirk Wallacher², Thomas Christian Hansen³, Holger Kohlmann¹

Affiliations

¹ Department of Inorganic Chemistry, Leipzig University , Johannisalle 29, 04103 Leipzig, Germany.
² Helmholtz Zentrum Berlin für Materialien und Energie , Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
³ Institut Laue-Langevin , 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France.

PMID: 28098993
DOI: 10.1021/acs.inorgchem.6b01945

Abstract

Hydrides (deuterides) of the CrB-type Zintl phases AeTt (Ae = alkaline earth; Tt = tetrel) show interesting bonding properties with novel polyanions. In SrGeD_4/3-x (γ phase), three zigzag chains of Ge atoms are condensed and terminated by covalently bound D atoms. A combination of in situ techniques (thermal analysis and synchrotron and neutron powder diffraction) revealed the existence of two further hydride (deuteride) phases with lower H (D) content (called α and β phases). Both are structurally related to the parent Zintl phase SrGe and to the ZrNiH structure type containing variable amounts of H (D) in Sr₄ tetrahedra. For α-SrGeD_y, the highest D content y = 0.29 was found at 575(2) K under 5.0(1) MPa of D₂ pressure, and β-SrGeD_y shows a homogeneity range of 0.47 < y < 0.63. Upon decomposition of SrGeD_4/3-x (γ-SrGeD_y), tetrahedral Sr₄ voids stay filled, while the Ge-bound D4 site loses D. When reaching the lower D content limit, SrGeD_4/3-x (γ phase) with 0.10 < x < 0.17, decomposes to the β phase. All three hydrides (deuterides) of SrGe show variable H (D) content.