Advancing the Ca14AlSb11 structure type: Synthesis and characterization of Yb14CdSb11 for thermoelectric applications

The ternary phase Yb14CdSb11 has been synthesized using both flux and polycrystalline methods. The crystal structure was determined via single-crystal X-ray diffraction, revealing that it crystallizes in the Ca14AlSb11 structure type (I41/acd space group with unit cell parameters of a = 16.5962(2) Å and c = 22.1346(5) Å, 90 K, Z = 8, R1 = 2.65 %: wR2 = 4.58 %. The polycrystalline form of the compound was synthesized from a stoichiometric reaction of Yb4Sb3, CdSb, Yb, and Sb. The elemental composition was confirmed using scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS), and phase purity was verified by powder X-ray diffraction (PXRD). Thermoelectric measurements, including resistivity, Seebeck coefficient, thermal conductivity, Hall carrier concentration, and Hall mobility, were conducted from 300 to 1273 K. Yb14CdSb11 exhibited a peak zT = 0.80 at 1150 K. Carrier concentration and Hall mobility ranged from to  holescm^-3^ and from 1019 cm²V-¹s-^¹, respectively. This carrier concentration is lower than that reported for the Zn or Mn analogs, leading to a lower thermoelectric figure of merit at high temperatures. However, with appropriate doping, it is expected that this phase should also be a promising p-type candidate for high-temperature energy conversion applications.