SEARCH

SEARCH BY CITATION

Keywords:

  • Alkaline earth metals;
  • Gallium;
  • Pnictides;
  • Solid-state structures;
  • Density functional calculations

Abstract

The focus of this paper is on the structural characterization of the new Zintl phases CaGa2P2, CaGa2As2, SrGa2As2, and Ba2Ga5As5, and the solid solution (Ba0.85(1)Sr0.15)2Ga5As5, all of which were synthesized from molten metal fluxes.CaGa2P2, CaGa2As2, and SrGa2As2 have layered structures with polyanionic layers made of ethane-like Ga2P6 and Ga2As6 motifs fused through common edges; the polyanionic substructure in Ba2Ga5As5 consists of condensed Ga2As6 units and GaAs4 tetrahedra. Ba4Ga5P8 and Ba4Ga5As8, another pair of new compounds with channel-like 3D structures, were also synthesized from metal fluxes, and their structures were established from single-crystal X-ray and synchrotron powder diffraction. They are based on GaP4 and GaAs4 tetrahedra, with parts of their structures being heavily disordered. The electronic structures computed with the linear muffin-tin orbital (LMTO) method are discussed as well, alongside the thermopower and the electrical conductivity, measured on single crystals of Ba2Ga5As5 and the solid solution (Ba0.85(1)Sr0.15)2 Ga5As5. They demonstrate that such an approach would be an effective way to fine-tune the transport properties.