Synthesis, Structure and Charge Transport Properties of Yb₅Al₂Sb₆: A Zintl Phase with Incomplete Electron Transfer

Abstract

We report the synthesis, structure, spectroscopic properties, charge and thermal transport, and electronic structure of a new member of the Zintl family, Yb(5)Al(2)Sb(6). The compound crystallizes in the Ba(5)Al(2)Bi(6) structure type and requires the addition of Ge or Si in the synthesis, which appears to act as a catalyst. Yb(5)Al(2)Sb(6) has an anisotropic structure with infinite anionic double chains cross-linked by Yb(2+) ions. Polycrystalline ingots of Yb(5)Al(2)Sb(6) prepared in the presence of 0.5 mol equiv of Ge showed room-temperature conductivity, thermopower, and thermal conductivity of approximately 1100 S/cm, approximately 20 microV/K, and approximately 3.8 W/m.K, respectively. Investigations of other solid solutions of Yb(5)Al(2)Sb(6), doping effects, and chemical modifications are discussed. Sr only partially replaces Yb in the structure leading to Sr(0.85)Yb(4.15)Al(2)Sb(6). Electronic structure calculations performed using a highly precise full-potential linearized augmented plane wave method within the density functional theory scheme show the presence of a negative band gap and suggest incomplete electron transfer and a metallic character to the compound.

Improved carrier concentration control in Zn-doped Ca5Al2Sb6

“…12 Many isostructural analogs of Ca 5 Al 2 Sb 6 exist, and a few have been studied for their electronic properties. [14][15][16] The complex structure (26 atoms in the primitive cell) and high mass contrast lead to low velocity phonon modes and the associated low lattice thermal conductivity.…”

Thermoelectric properties of the Zintl phases Yb5M2Sb6(M = Al, Ga, In)

“…All of the compounds with this structure type appear to be semiconducting with band gaps ranging from [18][19][20] In this structure type, the carrier concentrations can be controlled by doping, leading to promising thermoelectric properties. 13 23,25 In contrast, a recent investigation of the Ga analogue shows some evidence for semiconducting behavior. 24 In an attempt to resolve these conflicting reports and to present a comprehensive picture of the thermoelectric properties of this series, the current study investigates the high temperature electronic and thermal transport properties of the three Yb 5 M 2 Sb 6 compounds (M = Al, Ga, In) concurrently.…”

Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr3AlSb3

“…[15][16][17][18] Among A 5 M 2 Sb 6 compounds, most form either the Ca 5 Al 2 As 6 or Ca 5 Al 2 Bi 6 structure type. 19,20 These structure types both contain infinite chains of corner-linked MSb 4 tetrahedra in which neighboring chains are linked by Sb-Sb bonds to form ladder-like anionic structures. These two structure types differ only in the packing arrangement of the "ladders".…”