In Situ Hydrogenation of the Zintl Phase SrGe

Hydrides deuterides of the CrB type Zintl phases AeTt Ae alkaline earth; Tt tetrel show interesting bonding properties with novel polyanions. In SrGeD4 3 x amp; 947; 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 amp; 945; and amp; 946; 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 amp; 945; SrGeDy, the highest D content y 0.29 was found at 575 2 K under 5.0 1 MPa of D2 pressure, and amp; 946; SrGeDy shows a homogeneity range of 0.47 lt; y lt; 0.63. Upon decomposition of SrGeD4 3 x amp; 947; SrGeDy , tetrahedral Sr4 voids stay filled, while the Ge bound D4 site loses D. When reaching the lower D content limit, SrGeD4 3 x amp; 947; phase with 0.10 lt; x lt; 0.17, decomposes to the amp; 946; phase. All three hydrides deuterides of SrGe show variable H D conten