Interpenetrating icosahedra chains based zinc-rich ternary phases Ru4.0Sn2.9Zn11.6 and Ru3.0Sb0.97Zn11.0: synthesis, structures and physical properties

Abstract

Substituting of Ru with Sn and Sb in the phase RuZn₃ led to two new zinc-rich ternary compounds: Ru₄Sn_2.9Zn_11.6 (SnRZ: Monoclinic, C2/m, Pearson symbol oC46–δ, a = 6.8011(14), b = 7.9760(16), c = 11.083(2) Å, β = 97.56(3)°, Z = 2) and Ru_3.0Sb_0.97Zn_11.0 (SbRZ: Orthorhombic, Cmcm, Pearson symbol oC60, a = 7.8936(16), b = 6.8347(14), c = 16.904(3) Å, Z = 4). The structures of SnRZ and SbRZ are composed of four identical atomic layers but with different stacking sequences. They exhibit structural units of either three or two interpenetrating icosahedra fusing to form chains along the c axis. Their a and b lattice parameters are alike—interchanged in the chosen conventional setting—while the c parameters are related by c_SbRZ/2 × (1 + τ) ≈ 2c_SnRZ with τ = (1 + √5)/2 being the golden mean (known as τ-inflated phases). Both two compounds exhibit diamagnetic properties, and SnRZ and SbRZ congruently melt at 1296 K and 1233 K, respectively. Temperature-dependent resistivities reveal metallic behavior. The negative Seebeck coefficients indicate transport processes are dominated by electrons as carriers.