Synthesis and Structural Characterization of a Quaternary Zintl Phase Material from the Rb:Ge:In:As System: Rb(Ge_1.5ln_0.5)As₂(As_1.5Ge_0.5)

Abstract

In our investigations of new materials with potentially interesting electronic properties, we have synthesized the quaternary Zintl phase material Rb(Ge_1.5In_0.5)As₂(As_1.5Ge_0.5), (1), from Rb₃As₇, Ge and In at 700°C. The single crystal structure of 1 has been determined, and has been found to be a layered compound comprised of sheets of indium, germanium, and arsenic with the layers separated by interlamellar rubidium cations. The compounds Rb_XGe_2−XIn_XAs₄, (2), and K_XGe_2-XT1_XAs₄, (3) have also been synthesized and were also found to have layered structures. The structure of 1 was determined by single crystal X-ray diffraction: orthorhombic, Cmc2₁ (#36) with a = 3.799 (3) Å, b = 16.50 (2) Å, c = 12.24 (1) Å, V = 767 (1) ų, and pealed =4.589 g/cm³ for Z = 4. Least squares refinement of the model based on 322 observed reflections (I > 3.0σ(3(I)) and 45 variable parameters converged to R(R _W ) = 2.2% (2.6%). The tendency of the layered Zintl phases to undergo partial elemental substitution to achieve a closed shell electronic configuration is discussed.