Syntheses, crystal structure and physical properties of new Zintl phases Ba3T2As4 (T=Zn, Cd)

Through high temperature Pb-flux reactions, two new arsenide Zintl compounds, Ba3Zn2As4 and Ba3Cd2As4, were successfully obtained and their structures were accurately determined with Single-Crystal X-ray Diffraction. Both compounds are isotypic to Ba3Cd2Sb4 and crystallize in the monoclinic space group C2/m (No=12) with cell parameters of a=16.916(4)/17.089(3) Å, b=4.497(1)/4.6076(7) Å, c=7.225(2)/7.304(1) Å and β=113.147(2)/112.312(1) ° for Ba3Zn2As4 and Ba3Cd2As4, respectively. Electrical resistivity measurement on Ba3Cd2As4 reveals semiconducting behavior between 10 and 100 K, which results in a very small band gap of 0.01 eV. According to TG/DSC analyses, Ba3Cd2As4 exhibits good thermal stability and does not decompose below 950 K.

Graphic abstractA polyhedral view of the crystal structure for Ba3T2As4 (T=Zn or Cd) in which Ba and As atoms are plotted as purple and red spheres, respectively.Figure optionsDownload as PowerPoint slideHighlights
► Two new ternary Zintl compounds, Ba3Zn2As4 and Ba3Cd2As4, have been synthesized.
► Their structure features polyanionic layers constructed through [MAs4] tetrahedra.
► Ba3Cd2As4 has a very narrow band gap of 0.01 eV and are thermally stable up to 950 K.