Analysis of Nanostructuring in High Figure‐of‐Merit Ag1–xPbmSbTe2+m Thermoelectric Materials

Thermoelectric materials based on quaternary compounds Ag1−xPbmSbTe2+m exhibit high dimensionless figure-of-merit values, ranging from 1.5 to 1.7 at 700 K. The primary factor contributing to the high figure of merit is a low lattice thermal conductivity, achieved through nanostructuring during melt solidification. As a consequence of nucleation and growth of a second phase, coherent nanoscale inclusions form throughout the material, which are believed to result in scattering of acoustic phonons while causing only minimal scattering of charge carriers. Here, characterization of the nanosized inclusions in Ag0.53Pb18Sb1.2Te20 that shows a strong tendency for crystallographic orientation along the {001} planes, with a high degree of lattice strain at the interface, consistent with a coherent interfacial boundary is reported. The inclusions are enriched in Ag relative to the matrix, and seem to adopt a cubic, 96 atom per unit cell Ag2Te phase based on the Ti2Ni type structure. In-situ high-temperature synchrotron radiation diffraction studies indicated that the inclusions remain thermally stable to at least 800 K.

[1]  D. Rowe,et al.  Boundary scattering of phonons , 1978 .

[2]  M. Kanatzidis,et al.  Cubic AgPbmSbTe2+m: Bulk Thermoelectric Materials with High Figure of Merit , 2004, Science.

[3]  Matthew J. Kramer,et al.  In-situ elevated-temperature TEM study of (AgSbTe2)15(GeTe)85 , 2007 .

[4]  M. Kanatzidis,et al.  Coexistence of large thermopower and degenerate doping in the nanostructured material Ag0.85SnSb1.15Te3 , 2006 .

[5]  Min Zhou,et al.  High-performance Ag0.8Pb18+xSbTe20 thermoelectric bulk materials fabricated by mechanical alloying and spark plasma sintering , 2006 .

[6]  M. Kanatzidis,et al.  Strong Reduction of Thermal Conductivity in Nanostructured PbTe Prepared by Matrix Encapsulation , 2006 .

[7]  G. J. Snyder,et al.  Complex thermoelectric materials. , 2008, Nature materials.

[8]  Cronin B. Vining,et al.  A model for the high‐temperature transport properties of heavily doped n‐type silicon‐germanium alloys , 1991 .

[9]  Cronin B. Vining,et al.  Thermoelectric properties of pressure-sintered Si0.8Ge0.2 thermoelectric alloys , 1991 .

[10]  F. D. Rosi,et al.  Semiconductor materials for thermoelectric power generation up to 700 C , 1960, Electrical Engineering.

[11]  Fei Ren,et al.  Nanostructured Thermoelectric Materials and High-Efficiency Power-Generation Modules , 2007 .

[12]  Ctirad Uher,et al.  Spinodal decomposition and nucleation and growth as a means to bulk nanostructured thermoelectrics: enhanced performance in Pb(1-x)Sn(x)Te-PbS. , 2007, Journal of the American Chemical Society.

[13]  J. Verhoeven Fundamentals of Physical Metallurgy , 1975 .

[14]  G. Cody,et al.  Thermal Conductivity of Ge-Si Alloys at High Temperatures , 1962 .

[15]  Arun Majumdar,et al.  Nanostructuring expands thermal limits , 2007 .

[16]  R. Venkatasubramanian,et al.  Thin-film thermoelectric devices with high room-temperature figures of merit , 2001, Nature.

[17]  K. Easterling,et al.  Phase Transformations in Metals and Alloys , 2021 .

[18]  M. Toprak,et al.  The Impact of Nanostructuring on the Thermal Conductivity of Thermoelectric CoSb3 , 2004 .

[19]  M. J. Kramer,et al.  Nature of the cubic to rhombohedral structural transformation in (AgSbTe2)15(GeTe)85 thermoelectric material , 2007 .

[20]  M. P. Walsh,et al.  Quantum Dot Superlattice Thermoelectric Materials and Devices , 2002, Science.

[21]  Kang L. Wang,et al.  Thermoelectric figure of merit enhancement in a quantum dot superlattice , 2000 .

[22]  M. Kramer A strategy for rapid analysis of the variations in the reduced distribution function of liquid metals and metallic glasses , 2007 .

[23]  Kuei-Fang Hsu,et al.  Nanostructuring, compositional fluctuations, and atomic ordering in the thermoelectric materials AgPb(m)SbTe(2+m). The myth of solid solutions. , 2005, Journal of the American Chemical Society.

[24]  Min Zhou,et al.  Nanostructured AgPb(m)SbTe(m+2) system bulk materials with enhanced thermoelectric performance. , 2008, Journal of the American Chemical Society.

[25]  Sossina M. Haile,et al.  Zintl Phases as Thermoelectric Materials: Tuned Transport Properties of the Compounds CaxYb1–xZn2Sb2 , 2005 .

[26]  B. Sales Electron Crystals and Phonon Glasses: A New Path to Improved Thermoelectric Materials , 1998 .