AgSn[Bi1−xSbx]Se3: Synthesis, Structural Characterization, and Electrical Behavior

Paulina Valencia-Gálvez,Inmaculada Álvarez-Serrano,Daniela Delgado,María Luisa López,Antonio Galdámez,Silvana Moris

doi:10.3390/cryst11080864

Paulina Valencia-Gálvez, Inmaculada Álvarez-Serrano + Show 4 more

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https://doi.org/10.3390/cryst11080864

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Abstract

Herein, we report the synthesis, characterization, and electrical properties of lead-free AgSnm[Bi1−xSbx]Se2+m (m = 1, 2) selenides. Powder X-ray diffraction patterns and Rietveld refinement data revealed that these selenides consisted of phases related to NaCl-type crystal structure. The microstructures and morphologies of the selenides were investigated by backscattered scanning electron microscopy, energy-dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. The studied AgSnm[Bi1−xSbx]Se2+m systems exhibited typical p-type semiconductor behavior with a carrier concentration of approximately ~+1020 cm−3. The electrical conductivity of AgSnm[Bi1−xSbx]Se2+m decreased from ~3.0 to ~10−3 S·cm−1 at room temperature (RT) with an increase in m from 1 to 2, and the Seebeck coefficient increased almost linearly with increasing temperature. Furthermore, the Seebeck coefficient of AgSn[Bi1−xSbx]Se3 increased from ~+36 to +50 μV·K−1 with increasing Sb content (x) at RT, while its average value determined for AgSn2[Bi1−xSbx]Se4 was approximately ~+4.5 μV·K−1.

Highlights

IntroductionAgPbmSbTe2+m is a class of candidates for thermoelectric materials, which is often abbreviated as LAST (lead, antimony, silver, tellurium)-m
The multicomponent silver chalcogenide family AgM1M2Q3 (M1 = Pb, Sn; M2 = Bi, Sb, and Q = S, Se, Te) contains several thermoelectric phases [1,2,3,4,5,6,7]
Electron diffraction and energy-dispersive X-ray spectroscopy (EDS) analyses demonstrated that Ag-Sb-rich nanostructures were embedded into the PbTeand AgSbTe2: (PbTe) lattice of (PbTe)m–AgSbTe2 systems, whose electronic behaviors were sensitive to their microstructures

Summary

Introduction

AgPbmSbTe2+m is a class of candidates for thermoelectric materials, which is often abbreviated as LAST (lead, antimony, silver, tellurium)-m. These compounds can be envisioned as an alloy between two cubic chalcogenides, PbTeand AgSbTe2: (PbTe)m–AgSbTe2. Dutta et al and Cai et al reported the thermoelectric properties of n-type AgPbBiSe3 and p-type AgPbmSbSe2+m families [11,12]. These phases possess high Seebeck coefficients S equal to approximately −131 μV·K−1 (AgPbBiSe3) and +130 μV·K−1 (AgPbmSbSe2+m; m = 10). Electron diffraction and energy-dispersive X-ray spectroscopy (EDS) analyses demonstrated that Ag-Sb-rich nanostructures were embedded into the PbTe lattice of (PbTe)m–AgSbTe2 systems, whose electronic behaviors were sensitive to their microstructures

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