Structural Characterization and Thermoelectric Properties of Br-Doped AgSnm[Sb0.8Bi0.2]Te2+m Systems

Autor: Daniela Delgado, Silvana Moris, Paulina Valencia-Gálvez, María Luisa López, Inmaculada Álvarez-Serrano, Graeme R. Blake, Antonio Galdámez
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Materials, Vol 16, Iss 15, p 5213 (2023)
Druh dokumentu: article
ISSN: 1996-1944
DOI: 10.3390/ma16155213
Popis: Herein, we report the synthesis, structural and microstructural characterization, and thermoelectric properties of AgSnm[Sb0.8Bi0.2]Te2+m and Br-doped telluride systems. These compounds were prepared by solid-state reaction at high temperature. Powder X-ray diffraction data reveal that these samples exhibit crystal structures related to the NaCl-type lattice. The microstructures and morphologies are investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), and high-resolution transmission electron microscopy (HRTEM). Positive values of the Seebeck coefficient (S) indicate that the transport properties are dominated by holes. The S of undoped AgSnm[Sb0.8Bi0.2]Te2+m ranges from +40 to 57 μV·K−1. Br-doped samples with m = 2 show S values of +74 μV·K−1 at RT, and the Seebeck coefficient increases almost linearly with increasing temperature. The total thermal conductivity (κtot) monotonically increases with increasing temperature (10–300 K). The κtot values of undoped AgSnm[Sb0.8Bi0.2]Te2+m are ~1.8 W m−1 K−1 (m = 4) and ~1.0 W m−1 K−1 (m = 2) at 300 K. The electrical conductivity (σ) decreases almost linearly with increasing temperature, indicating metal-like behavior. The ZT value increases as a function of temperature. A maximum ZT value of ~0.07 is achieved at room temperature for the Br-doped phase with m = 4.
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