Spinodal Decomposition and Nucleation and Growth as a Means to Bulk Nanostructured Thermoelectrics:  Enhanced Performance in Pb1-xSnxTe−PbS

Androulakis, J.; Lin, Chia Her; Kong, Hun Jin; Uher, Ctirad; Wu, Chun I.; Hogan, Timothy P.; Cook, B. A.; Caillat, T.; Paraskevopoulos, K. M.; Kanatzidis, Mercouri G.

doi:10.1021/ja071875h

Cited by 421 publications

(350 citation statements)

References 49 publications

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“…Lead chalcogenides and their alloys can be engineered to exhibit high ZTs; however, environmental concern regarding Pb prevents their deployment in large-scale applications (6)(7)(8)(9)(10). Tin telluride (SnTe), a lead-free IV-VI narrow band-gap semiconductor has not been considered favorably as a good thermoelectric material because of its low ZT due to the relatively low Seebeck coefficient and high electronic thermal conductivity caused by intrinsic Sn vacancies (11)(12)(13), although SnTe has been used to alloy with other tellurides for better TE properties (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26). Even though there has been no real success in achieving good TE properties of lead-free SnTe, the similarity between the electronic band structure of SnTe and that of PbTe and PbSe (27)(28)(29)(30)(31) suggests it has the potential to be a good TE material, especially given the two valence bands (light-hole and heavy-hole bands) that contribute to the hole density of states.…”

Section: G Ood Thermoelectric (Te) Materials Should Not Only Have Highmentioning

confidence: 99%

High thermoelectric performance by resonant dopant indium in nanostructured SnTe

Zhang

Liao

Lan

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

648

765

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From an environmental perspective, lead-free SnTe would be preferable for solid-state waste heat recovery if its thermoelectric figure-of-merit could be brought close to that of the leadcontaining chalcogenides. In this work, we studied the thermoelectric properties of nanostructured SnTe with different dopants, and found indium-doped SnTe showed extraordinarily large Seebeck coefficients that cannot be explained properly by the conventional two-valence band model. We attributed this enhancement of Seebeck coefficients to resonant levels created by the indium impurities inside the valence band, supported by the firstprinciples simulations. This, together with the lower thermal conductivity resulting from the decreased grain size by ball milling and hot pressing, improved both the peak and average nondimensional figure-of-merit (ZT) significantly. A peak ZT of ∼1.1 was obtained in 0.25 atom % In-doped SnTe at about 873 K.

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Section: G Ood Thermoelectric (Te) Materials Should Not Only Have Highmentioning

confidence: 99%

High thermoelectric performance by resonant dopant indium in nanostructured SnTe

Zhang

Liao

Lan

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

648

765

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“…[8][9][10][11][12] This approach led to a peak zT of 1.4$1.7 in both p-10,13,14 and n-type 8,15,16 PbTe materials.…”

Section: Broader Contextmentioning

confidence: 99%

Combination of large nanostructures and complex band structure for high performance thermoelectric lead telluride

Pei

Heinz

LaLonde

et al. 2011

Energy Environ. Sci.

155

112

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The complexity of the valence band structure in p-type PbTe has been shown to enable a significant enhancement of the average thermoelectric figure of merit (zT) when heavily doped with Na. It has also been shown that when PbTe is nanostructured with large nanometer sized Ag 2 Te precipitates there is an enhancement of zT due to phonon scattering at the interfaces. The enhancement in zT resulting from these two mechanisms is of similar magnitude but, in principle, decoupled from one another. This work experimentally demonstrates a successful combination of the complexity in the valence band structure with the addition of nanostructuring to create a high performance thermoelectric material. These effects lead to a high zT over a wide temperature range with peak zT > 1.5 at T > 650 K in Na-doped PbTe/Ag 2 Te. This high average zT produces 30% higher efficiency (300-750 K) than pure Na-doped PbTe because of the nanostructures, while the complex valence band structure leads to twice the efficiency as the related n-type La-doped PbTe/Ag 2 Te without such band structure complexity. Thermoelectric (TE) applications have attracted increasing interest in the last decade as a means to combat the ever growing rate of energy consumption throughout the world. The two main applications for thermoelectric materials are power generation, which utilizes the Seebeck effect, and solid state cooling, which has its roots in the Peltier effect. In recent years, thermoelectric power generation has been a prime interest to the automotive industry 1 as a sustainable and emission free route to vehicular waste heat recovery. The effectiveness of this process is restricted by the overall efficiency of the thermoelectric materials.On a materials level, the efficiency of the thermal to electrical energy conversion is determined by the thermoelectric figure of, where S, s, k E and k L are the Seebeck coefficient, electrical conductivity, and the electronic and lattice components of the thermal conductivity. Since S, s and k E have an intimate relationship with the carrier density, 1,2 the grand challenge in designing thermoelectric materials is the decoupling of electronic and thermal properties. Many methods to achieve a large power factor (S 2 s) or to reduce the thermal conductivity were proven to be successful, but combination of these two effects is difficult. As a result, the current best commercially available thermoelectric materials have a peak zT near unity.A number of mechanisms have been proposed to explain high zT in p-type PbTe. The Tl-doping in PbTe:Tl produces resonant electronic states that enhances the Seebeck coefficient, but reduces hole mobility 3 and has zT $ 1.4 at 500 C. Na-doped PbTe:Na, 4 without resonant states, 5,6 has similarly high zT that Materials Science, California Institute of Technology, Pasadena, CA, 91125, USA. E-mail: jsnyder@caltech.edu Broader contextThermoelectric generators, which directly convert heat into electricity are being considered for industrial or automotive waste heat recovery. However, th...

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“…[1][2][3][4][5][6][7][8][9][10][11][12] The prototypical example is PbTe, with a approaching 1.0. 13 It has recently been shown that alloying PbTe with other semiconductor systems can increase the figure of merit through the formation of nanoscale precipitates, which reduce the lattice thermal conductivity, , of the system without significantly reducing the electronic conductivity, .…”

Section: Introductionmentioning

confidence: 99%

“…13 It has recently been shown that alloying PbTe with other semiconductor systems can increase the figure of merit through the formation of nanoscale precipitates, which reduce the lattice thermal conductivity, , of the system without significantly reducing the electronic conductivity, . 7,11 This lack of carrier scattering has been attributed to coherent interfaces between PbS-rich precipitates and the PbTe-rich matrix. 7,14 A coherent interface between two phases maintains a common (possibly strained) lattice between the phases which is not broken by misfit dislocations.…”

Section: Introductionmentioning

confidence: 99%

Coherent and incoherent phase stabilities of thermoelectric rocksalt IV-VI semiconductor alloys

Doak

Wolverton

2012

Phys. Rev. B

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Nanostructures formed by phase separation improve the thermoelectric figure of merit in lead chalcogenide semiconductor alloys, with coherent nanostructures giving larger improvements than incoherent nanostructures. However, large coherency strains in these alloys drastically alter the thermodynamics of phase stability. Incoherent phase stability can be easily inferred from an equilibrium phase diagram, but coherent phase stability is more difficult to assess experimentally. Therefore, we use density functional theory calculations to investigate the coherent and incoherent phase stability of the IV-VI rocksalt semiconductor alloy systems Pb(S,Te), Pb(Te,Se), Pb(Se,S), (Pb,Sn)Te, (Sn,Ge)Te, and (Ge,Pb)Te. Here we use the term coherent to indicate that there is a common and unbroken lattice between the phases under consideration, and we use the term incoherent to indicate that the lattices of coexisting phases are unconstrained and allowed to take on equilibrium volumes. We find that the thermodynamic ground state of all of the IV-VI pseudo-binary systems studied is incoherent phase separation. We also find that the coherency strain energy, previously neglected in studies of these IV-VI alloys, is lowest along 111 (in contrast to most fcc metals), and is a large fraction of the thermodynamic driving force for incoherent phase separation in all systems. The driving force for coherent phase separation is significantly reduced, and we find that coherent nanostructures can only form at low temperatures where kinetics may prohibit their precipitation. Furthermore, by calculating the energies of ordered structures for these systems we find that the coherent phase stability of most IV-VI systems favors ordering over spinodal decomposition. Our results suggest that experimental reports of spinodal decomposition in the IV-VI rocksalt alloys should be re-examined. PACS number(s): 64.75. Nx, 82.60.Nh, 84.60.Rb, 64.70.kg 2

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Spinodal Decomposition and Nucleation and Growth as a Means to Bulk Nanostructured Thermoelectrics: Enhanced Performance in Pb_1-_xSn_xTe−PbS

Cited by 421 publications

References 49 publications

High thermoelectric performance by resonant dopant indium in nanostructured SnTe

High thermoelectric performance by resonant dopant indium in nanostructured SnTe

Combination of large nanostructures and complex band structure for high performance thermoelectric lead telluride

Coherent and incoherent phase stabilities of thermoelectric rocksalt IV-VI semiconductor alloys

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