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Keywords:

  • Zintl phases;
  • Hydrides;
  • Interstitials;
  • Crystal growth;
  • Flux growth

Abstract

Reactions of germanium in calcium/lithium flux yield crystals of new complex hydrides, with hydrogen incorporated either inadvertently due to traces of hydride contaminants in the flux metals, or deliberately by the addition of CaH2 as a reactant. The new germanide hydride Zintl phase LiCa7Ge3H3 crystallizes in the orthorhombic space group Pnma [a = 9.8599(2) Å, b = 13.7716(3) Å, c = 8.7430(2) Å; Z = 4; R1 = 0.0195]. The structure features isolated Ge4– anions surrounded by calcium ions, and hydride anions in octahedral sites defined by Ca and Li ions. Another product thatappears in these reactions was found to form from incorporation of both oxide and hydride impurities. This phase,LiCa11Ge3OHx (x ≈ 4) forms in the tetragonal space group P42/nmc [a = 15.832(2) Å, c = 13.694(2) Å; Z = 8; R1 = 0.0350]. In addition to isolated Ge4– and octahedral H anions, the structure also features incorporation of oxide anions in octahedral sites.