Tailoring Thermoelectric Transport Properties of Ag-Alloyed PbTe: Effects of Microstructure Evolution

Sheskin, Ariel; Schwarz, Torsten; Yu, Yuan; Zhang, Siyuan; Abdellaoui, Lamya; Gault, Baptiste; Cojocaru‐Mirédin, Oana; Scheu, Christina; Raabe, Dierk; Wuttig, Matthias; Amouyal, Yaron

doi:10.1021/acsami.8b15204

Cited by 19 publications

(7 citation statements)

References 43 publications

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“…Dopant aggregates (which do not necessarily constitute a secondary phase) appear with a number density of 1.6 × 10 17 cm −3 in the Te‐rich sample versus 4.1 × 10 16 cm −3 in the Pb‐rich sample. Past works on Pb chalcogenides doped with embrittling Ag, Cu, Na, and/or Eu dopants find similar dopant aggregation [ 29–32,64 ] and similar features are responsible for age hardening in structural Al‐based and reactor alloys. [ 65,66 ] While APT can not identify the non‐hardening n‐type dopant iodine (I and Te are indiscernible in APT), Bi and La appear to distribute homogenously in PbTe.…”

Section: Resultsmentioning

confidence: 99%

Dislocations Stabilized by Point Defects Increase Brittleness in PbTe

Male

Abdellaoui

et al. 2021

Adv Funct Materials

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Dislocations and the residual strain they produce are instrumental for the high thermoelectric figure of merit, zT ≈ 2, in lead chalcogenides. However, these materials tend to be brittle, barring them from practical green energy and deep space applications. Nonetheless, the bulk of thermoelectrics research focuses on increasing zT without considering mechanical performance. Optimized thermoelectric materials always involve high point defect concentrations for doping and solid solution alloying. Brittle materials show limited plasticity (dislocation motion), yet clear links between crystallographic defects and embrittlement are hitherto unestablished in PbTe. This study identifies connections between dislocations, point defects, and the brittleness (correlated with Vickers hardness) in single crystal and polycrystalline PbTe with various n‐ and p‐type dopants. Speed of sound measurements show a lack of electronic bond stiffening in p‐type PbTe, contrary to the previous speculation. Instead, varied routes of point defect–dislocation interaction restrict dislocation motion and drive embrittlement: dopants with low doping efficiency cause high defect concentrations, interstitial n‐type dopants (Ag and Cu) create highly strained obstacles to dislocation motion, and highly mobile dopants can distribute inhomogeneously or segregate to dislocations. These results illustrate the consequences of excessive defect engineering and the necessity to consider both mechanical and thermoelectric performance when researching thermoelectric materials for practical applications.

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Section: Resultsmentioning

confidence: 99%

Dislocations Stabilized by Point Defects Increase Brittleness in PbTe

Male

Abdellaoui

et al. 2021

Adv Funct Materials

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“…The typical size of these Te-nanoprecipitates is ∼8–10 nm, based on micrographs taken from different positions. The precipitate number density is evaluated by counting the number of precipitates shown in different micrographs per unit area (e.g., the red spots in Figure c) and translating it into a number per unit volume, assuming homogeneous distribution, resulting in N v ∼ 2.45 × 10 23 m –3 . − Inspection of the TEM micrographs also reveals several crystalline domains with numerous GBs (Figure f,g). The crystalline structure of Bi 2 Te 3 is clearly visible in the high-magnification TEM micrograph and FFT patterns of Bi 2 Te 3 and Te shown in the insets of Figure f,g, in agreement with the XRD analysis.…”

Section: Resultsmentioning

confidence: 99%

Development of Nanostructured Bi₂Te₃ with High Thermoelectric Performance by Scalable Synthesis and Microstructure Manipulations

Gayner

Menezes

Natanzon

et al. 2023

ACS Appl. Mater. Interfaces

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Nanostructuring of thermoelectric (TE) materials leads to improved energy conversion performance; however, it requires a perfect fit between the nanoprecipitates’ chemistry and crystal structure and those of the matrix. We synthesize bulk Bi2Te3 from molecular precursors and characterize their structure and chemistry using electron microscopy and analyze their TE transport properties in the range of 300–500 K. We find that synthesis from Bi2O3 + Na2TeO3 precursors results in n-type Bi2Te3 containing a high number density (N v ∼ 2.45 × 1023 m–3) of Te-nanoprecipitates decorating the Bi2Te3 grain boundaries (GBs), which yield enhanced TE performance with a power factor (PF) of ∼19 μW cm–1 K–2 at 300 K. First-principles calculations validate the role of Te/Bi2Te3 interfaces in increasing the charge carrier concentration, density of states, and electrical conductivity. These optimized TE coefficients yield a promising TE figure of merit (zT) peak value of 1.30 at 450 K and an average zT of 1.14 from 300 to 500 K. This is one of the cutting-edge zT values recorded for n-type Bi2Te3 produced by chemical routes. We believe that this chemical synthesis strategy will be beneficial for future development of scalable n-type Bi2Te3 based devices.

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“…First, a certain time is required for the establishment of steady‐state. [ 115 ] Second, the thermovoltage response to ∆T is proportional reproducible, implying the reliability of homemade instruments. Figure 7h shows the direct plots of thermovoltage versus ∆ T , which behave excellent linear correlations.…”

Section: Properties Of I‐te Materialsmentioning

confidence: 99%

Advances in Ionic Thermoelectrics: From Materials to Devices

Sun

Shi

et al. 2023

Advanced Energy Materials

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technology, which can literally convert ambient heat into high value-added electricity. [2] Compared to its analogous heatto-electricity technologies, TE takes the advantage of light weight, quietness, zero pollution emission, and an infinite lifetime (Figure 1b), making it ideal for selfpowering applications that are equipped on human body or installed in rural areas. [3] The performance of TE devices is mainly governed by the dimensionless figure-of-merit of their constituent TE materials, defined as ZT = S 2 σT/κ, where T refers to absolute temperature, S, σ, and κ are the Seebeck coefficient, electrical conductivity, and thermal conductivity, respectively. [4] Practically, "Z" reflects the premise of TE materials being used for power generation, namely as a thermoelectric generator, while "T" regulates the working temperature under which heat transfer is valid. [5] As can be seen in Figure 1c, TE materials with high heat transfer property and a Z of >10 −3 K −1 (corresponds to ZT > 0.3 at room temperature) are suitable for making temperature sensors; in comparison, TE materials with a much higher Z of 10 −2 K −1 (corresponds to ZT > 3 at room temperature) and low heat transfer property are preferable for making wearable devices.On the attainment of satisfactory Z value, a large S, which is proportional to the magnitude of thermovoltage per temperature difference (∆T), is highly desirable. However, the S of conventional electronic thermoelectric (e-TE) materials is limited to an order of 10 1 -10 2 µV K −1 due to relatively low electronic enthalpy of inorganic materials, i.e., the S of electron gas is merely ≈87.5 µV K −1 at room temperature. [6] Considering a small ∆T of 20 °C as that between human skin and ambient environment, more than 100 inorganic TE legs are required to work comparably with a 1.5 V solid battery via calculation, which indicates that e-TE materials are unsuitable for low-grade (<130 °C) applications. As most of waste heat is emitted from low-grade sources such as industrial plants and vehicle exhaust, traditional e-TE devices are in niche market. As another form of charge carrier, ions can induce a much larger S in an order of a few mV K −1 due to higher ionic enthalpy than electronic enthalpy. [7] As a result, an ionic thermoelectric (i-TE) device needs only ≈8 legs to generate a 1.5 V voltage at a ∆T of 20 °C, indicating that i-TE device is feasible for microminiaturization and can be incorporated with wearable devices and electronic skins. Other advantages of i-TEs over e-TEs include i) good flexibility stemming from the normally organic matrix, As an extended member of the thermoelectric family, ionic thermoelectrics (i-TEs) exhibit exceptional Seebeck coefficients and applicable power factors, and as a result have triggered intensive interest as a promising energy conversion technique to harvest and exploit low-grade waste heat (<130 °C). The last decade has witnessed great progress in i-TE materials and devices; however, there are ongoing disputes about the inherent fundamentals ...

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Tailoring Thermoelectric Transport Properties of Ag-Alloyed PbTe: Effects of Microstructure Evolution

Cited by 19 publications

References 43 publications

Dislocations Stabilized by Point Defects Increase Brittleness in PbTe

Dislocations Stabilized by Point Defects Increase Brittleness in PbTe

Development of Nanostructured Bi₂Te₃ with High Thermoelectric Performance by Scalable Synthesis and Microstructure Manipulations

Advances in Ionic Thermoelectrics: From Materials to Devices

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Tailoring Thermoelectric Transport Properties of Ag-Alloyed PbTe: Effects of Microstructure Evolution

Cited by 19 publications

References 43 publications

Dislocations Stabilized by Point Defects Increase Brittleness in PbTe

Dislocations Stabilized by Point Defects Increase Brittleness in PbTe

Development of Nanostructured Bi2Te3 with High Thermoelectric Performance by Scalable Synthesis and Microstructure Manipulations

Advances in Ionic Thermoelectrics: From Materials to Devices

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Development of Nanostructured Bi₂Te₃ with High Thermoelectric Performance by Scalable Synthesis and Microstructure Manipulations