Realizing the High Thermoelectric Performance of GeTe by Sb-Doping and Se-Alloying

Li, Juan; Zhang, Xinyue; Lin, Siqi; Chen, Zhiwei; Pei, Yanzhong

doi:10.1021/acs.chemmater.6b04066

Cited by 251 publications

(321 citation statements)

References 78 publications

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“…The resistivity and Hall coefficient were measured using the Van der Pauw technique under a reversible magnetic field of 1.5 T. The Seebeck coefficient was obtained from the slope of the thermopower vs temperature gradient from 0 to 5 K. 68 The thermal diffusivity (D) was measured by a laser flash technique (model: LFA-457, Netzsch, Selb, Germany). A Dulong-Petit limit of the heat capacity (C p ) is used, which is consistent with the measurements 40 for GeTe alloys and with those in many recent reports 47,69,70 The thermal conductivity is determined via κ = dC p D, where d is Table 1 Calculated band parameters for GeTe, PbTe and SnTe Thermoelectric performance of p-type GeTe J Li et al the density. All of the transport property measurements were carried out from 300 to 800 K, and the reproducibility is confirmed by multiple measurements on the same sample and in multiple samples with similar carrier concentrations.…”

Section: Methodssupporting

confidence: 62%

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

et al. 2017

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PbTe and SnTe in their p-type forms have long been considered high-performance thermoelectrics, and both of them largely rely on two valence bands (the first band at L point and the second one along the Σ line) participating in the transport properties. This work focuses on the thermoelectric transport properties inherent to p-type GeTe, a member of the group IV monotellurides that is relatively less studied. Approximately 50 GeTe samples have been synthesized with different carrier concentrations spanning from 1 to 20 × 10 20 cm − 3 , enabling an insightful understanding of the electronic transport and a full carrier concentration optimization for the thermoelectric performance. When all of these three monotellurides (PbTe, SnTe and GeTe) are fully optimized in their p-type forms, GeTe shows the highest thermoelectric figure of merit (zT up to 1.8). This is due to its superior electronic performance, originating from the highly degenerated Σ band at the band edge in the low-temperature rhombohedral phase and the smallest effective masses for both the L and Σ bands in the high-temperature cubic phase. The high thermoelectric performance of GeTe that is induced by its unique electronic structure not only provides a reference substance for understanding existing research on GeTe but also opens new possibilities for the further improvement of the thermoelectric performance of this material.

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Section: Methodssupporting

confidence: 62%

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

et al. 2017

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“…For example, Bi and Sb have been reported to be effective donors to decrease the carrier concentration. [ 39,46 ] Alternatively, many efforts also have been made on increasing the formation energy of Ge vacancies for direct reduction of the hole concentration. Pb substitution has been demonstrated to have the effect to increase the formation energy of Ge vacancy and dissolve Ge precipitates to reduce the intrinsic high hole concentration.…”

Section: Introductionmentioning

confidence: 99%

Manipulating the Ge Vacancies and Ge Precipitates through Cr Doping for Realizing the High‐Performance GeTe Thermoelectric Material

Shuai

Sun

Tan

et al. 2020

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GeTe alloy is a promising medium‐temperature thermoelectric material but with highly intrinsic hole carrier concentration by thermodynamics, making this system to be intrinsically off‐stoichiometric with Ge vacancies and Ge precipitations. Generally, an intentional increase of formation energy of Ge vacancy by element substitution will lead to an effective dissolution of Ge precipitates for reduction in hole concentration. Here, an opposite direction of decreasing the formation energy of Ge vacancies is demonstrated by substituting Cr at Ge site. This strategy produces more but nearly homogenously distributed Ge precipitations and Ge vacancies, which provides enhanced phonon scattering and effectively reduces the lattice thermal conductivity. Furthermore, Cr atom carries one more electron than Ge and serves as an electron donor for decreasing the hole carrier concentrations. Further optimization incorporates the effect of Bi substitution for facilitating band convergence. A maximum figure of merit (ZT) of 2.0 at 600 K with average ZT of over 1.2 is achieved in the sample of Ge0.92Cr0.03Bi0.05Te, making it one of the best thermoelectric materials for medium‐temperature application.

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“…Reports indicate that phonons having low-to mid-range frequencies (i.e., mid-to long-wavelength range) can be significantly scattered by nanostructured features, such as precipitates [10], whereas high-frequency phonons (i.e., of short wavelengths) are scattered by point defects mainly, e.g., solute atoms and vacancies [11]. In this sense, besides achieving direct enhancement of the TE performance, understanding basic physical behavior of lattice thermal conductivity of two-phase alloys based on PbTe is a grand challenge by itself.…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution of Ag-Alloyed PbTe-Based Compounds and Implications for Thermoelectric Performance

et al. 2017

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Abstract:We investigate the microstructure evolution of Ag-alloyed PbTe compounds for thermoelectric (TE) applications with or without additions of 0.04 at. % Bi. We control the nucleation and temporal evolution of Ag 2 Te-precipitates in the PbTe-matrix applying designated aging heat treatments, aiming to achieve homogeneous dispersion of precipitates with high number density values, hypothesizing that they act as phonon scattering centers, thereby reducing lattice thermal conductivity. We measure the temperature dependence of the Seebeck coefficient and electrical and thermal conductivities, and correlate them with the microstructure. It is found that lattice thermal conductivity of PbTe-based compounds is reduced by controlled nucleation of Ag 2 Te-precipitates, exhibiting a number density value as high as 2.7 × 10 20 m −3 upon 6 h aging at 380 • C. This yields a TE figure of merit value of ca. 1.4 at 450 • C, which is one on the largest values reported for n-type PbTe compounds. Subsequent aging leads to precipitate coarsening and deterioration of TE performance. Interestingly, we find that Bi-alloying improves the alloys' thermal stability by suppressing microstructure evolution, besides the role of Bi-atoms as electron donors, thereby maintaining high TE performance that is stable at elevated service temperatures. The latter has prime technological significance for TE energy conversion.

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Realizing the High Thermoelectric Performance of GeTe by Sb-Doping and Se-Alloying

Cited by 251 publications

References 78 publications

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

Manipulating the Ge Vacancies and Ge Precipitates through Cr Doping for Realizing the High‐Performance GeTe Thermoelectric Material

Microstructure Evolution of Ag-Alloyed PbTe-Based Compounds and Implications for Thermoelectric Performance

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