Zintl compounds with the Ca₁₄AlSb₁₁ structure type (14-1-11) have attracted interest for their excellent thermoelectric properties at high temperatures. However, few bismuth-containing 14-1-11 compounds have been reported and investigated for their thermoelectric properties. A new member of this family, Yb₁₄ZnBi₁₁, has been synthesized as single crystals using the lead-flux method. Single-crystal diffraction confirms that it belongs to the Ca₁₄AlSb₁₁ structure type and that it crystallizes in the tetragonal space group I4₁/acd (No. 142; Z = 8). Thermoelectric properties were measured on dense pellets of polycrystalline Yb₁₄ZnBi₁₁. It shows a low thermal conductivity of 0.77 W/m K at room temperature and a low electrical resistivity of 0.91 mOhm cm at 367 K. However, a low Seebeck coefficient results in overall low thermoelectric performance. The potential of Yb₁₄ZnBi₁₁ for thermoelectric applications highlights the vast array of unexplored compounds available in this structure type for future research.

Powder X-ray Diffraction

Powder X-ray Diffraction (PXRD) data collected at room temperature using a Bruker D8 ECO ADVANCE powder X-ray diffraction (PXRD) diffractometer on zero-background off-axis quartz plates. Cu Kα radiation was used with a step size of 0.02° over the 2θ angles of 20° to 80°.

Spark Plasma Sintering

After sieving the powder sample through a 100-mesh screen, it was loaded into a 12.7 mm graphite die. Initially, the powder was cold-pressed at 5 kN using a Dr. Sinter Junior Spark Plasma Sintering system (Fuji Electronic Industrial Co., LTD) under Ar gas. The applied force was increased to 9 kN, and the powder was sintered at 900 °C for 30 minutes. The resulting pellets exhibited a density greater than 98 %, measured by the Archimedes' principle.

Thermal Transport Properties

Thermal diffusivity was measured on the pressed pellets using a Netzsch LFA 475 Microflash under Ar flow. A graphite coating was applied to the pellets’ surface to ensure maximum absorption of the laser. The total thermal conductivity was then calculated using the equation, к = D × C_p × 𝜌. In this equation, D represents the measured thermal diffusivity, C_p denotes the heat capacity, and 𝜌 denotes the material's density. The heat capacity was approximated using the Dulong–Petit law.

Seebeck Coefficient and Electrical Resistivity

The Linseis LSR-3 instrument was utilized to measure the Seebeck coefficient and electrical resistivity of a bar that was cut from the pellet. For the measurements, Pt/Rh thermocouples were arranged in a four-probe configuration under a static helium atmosphere. Additionally, a polished zirconium ribbon was placed inside the susceptor to serve as an oxygen sponge, thereby protecting the sample’s integrity.