Hydrogenation products of the Zintl phases AeTt (Ae = alkaline earth; Tt = tetrel) exhibit hydride anions on interstitial sites as well as hydrogen covalently bound to Tt which leads to a reversible hydrogenation at mild conditions. In situ thermal analysis, synchrotron and neutron powder diffraction under hydrogen (deuterium for neutrons) pressure was applied to BaTt (Tt=Ge, Sn). BaTtHy (1<y<1.67, γ-phases) were formed at 5 MPa hydrogen pressure and elevated temperatures (400–450 K). Further heating (500–550 K) leads to a hydrogen release forming the new phases β-BaGeH0.5 (Pnma, a=1319.5(2) pm, b=421.46(2) pm, c=991.54(7) pm) and α-BaSnH0.19 (Cmcm, a=522.72(6) pm, b=1293.6(2) pm, c=463.97(6) pm). Upon cooling the hydrogen rich phases are reformed. Thermal decomposition of γ-BaGeHy under vacuum leads to β-BaGeH0.5 and α-BaGeH0.13 [Cmcm, a=503.09(3) pm, b=1221.5(2) pm, c=427.38(4) pm]. At 500 K the reversible reaction α-BaGeH0.23 (vacuum)⇄β-BaGeH0.5 (0.2 MPa deuterium pressure) is fast and was observed with 10 s time resolution by in situ neutron diffraction. The phases α-BaTtHy show a pronounced phase width (at least 0.09<y<0.36). β-BaGeH0.5 and the γ-phases appear to be line phases. The hydrogen poor (α- and β-) phases show a partial occupation of Ba4 tetrahedra by hydride anions leading to a partial oxidation of polyanions and shortening of Tt–Tt bonds.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:33411 |
| Date | 28 February 2019 |
| Creators | Auer, Henry, Weber, Sebastian, Hansen, Thomas Christian, Többens, Daniel Maria, Kohlmann, Holger |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/acceptedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 10.1515/zkri-2017-2142, 2196-7105 |
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