Dynamic doping and Cottrell atmosphere optimize the thermoelectric performance of n-type PbTe over a broad temperature interval

Yu, Yuan; Zhou, Chenyang; Zhang, Xiangzhao; Abdellaoui, Lamya; Doberstein, Christian; Berkels, Benjamin; Ge, Bangzhi; Qiao, Guanjun; Scheu, Christina; Wuttig, Matthias; Cojocaru‐Mirédin, Oana; Zhang, Siyuan

doi:10.1016/j.nanoen.2022.107576

Cited by 24 publications

(32 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This technique shows a much higher spatial resolution (sub-nanometer scale) and chemical sensitivity (ppm level) than that of EPMA and is particularly important for investigating GB microstructures. [13,[67][68][69] Besides, it provides information about the bond-rupture behavior and thus can distinguish metavalent bonding from other chemical bonding mechanisms. [27,70] Figure 4a shows a homogeneous distribution of Ge, Sb, Pb, and Te in 3D space for the sample x = 1%.…”

Section: Grain-boundary Ga Complexions Versus Precipitationsmentioning

confidence: 99%

Grain Boundary Complexions Enable a Simultaneous Optimization of Electron and Phonon Transport Leading to High‐Performance GeTe Thermoelectric Devices

Zhang

Gan

Wang

et al. 2022

Advanced Energy Materials

Self Cite

View full text Add to dashboard Cite

The heat-to-electricity conversion efficiency depends on the dimensionless figure-of-merit of materials, defined as ZT = S 2 σT/κ, where S, σ, and T are the Seebeck coefficient, the electrical conductivity, and the absolute temperature, respectively. The total thermal conductivity (κ) consists of the electronic thermal conductivity (κ e ) and the lattice thermal conductivity (κ l ). The ZT value is directly proportional to several physical para meters summarized in the so-called materials quality factor, B∝µ W /κ l , at a given carrier concentration (n), where the weighted mobility (µ W ) and κ l are determined by the transport properties of electrons and phonons, respectively. [5] Hence, it is desirable to maximize the weighted mobility and minimize the lattice thermal conductivity. Yet, similarities in performance change of thermal and electrical transport for thermoelectrics impede the improvement of B factor for high ZT, which is the key challenge in optimizing TE materials. [6] Sustained efforts have been undertaken to improve the TE properties of materials, such as band convergence, [7] resonant doping, [8] energy filtering, [9] high entropy, [10] and hierarchical microstructure engineering. [11] For polycrystalline bulk samples, the most ubiquitous defects are grain boundaries (GBs).Grain boundaries (GBs) form ubiquitous microstructures in polycrystalline materials which play a significant role in tuning the thermoelectric figure of merit (ZT). However, it is still unknown which types of GB features are beneficial for thermoelectrics due to the challenge of correlating complex GB microstructures with transport properties. Here, it is demonstrated that GB complexions formed by Ga segregation in GeTe-based alloys can optimize electron and phonon transport simultaneously. The Ga-rich complexions increase the power factor by reducing the GB resistivity with slightly improved Seebeck coefficients. Simultaneously, they lower the lattice thermal conductivity by strengthening the phonon scattering. In contrast, Ga 2 Te 3 precipitates at GBs act as barriers to scatter both phonons and electrons and are thus unable to improve ZT. Tailoring GBs combined with the beneficial alloying effects of Sb and Pb enables a peak ZT of ≈2.1 at 773 K and an average ZT of 1.3 within 300-723 K for Ge 0.78 Ga 0.01 Pb 0.1 Sb 0.07 Te. The corresponding thermoelectric device fabricated using 18-pair p-n legs shows a power density of 1.29 W cm −2 at a temperature difference of 476 K. This work indicates that GB complexions can be a facile way to optimize electron and phonon transport, further advancing thermoelectric materials.

show abstract

Section: Grain-boundary Ga Complexions Versus Precipitationsmentioning

confidence: 99%

Grain Boundary Complexions Enable a Simultaneous Optimization of Electron and Phonon Transport Leading to High‐Performance GeTe Thermoelectric Devices

Zhang

Gan

Wang

et al. 2022

Advanced Energy Materials

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is worth noting that at temperatures above 623 K, there is an abrupt drop of κ lat , particularly for samples with higher Cu concentrations, as described in Figure b. This can be attributed to the dynamic migration of highly mobile Cu atoms from Cu 2 Se precipitates (fast ion conductors) to the interstitial sites of PbSe upon warming, which is akin to the case of Ag 2 Te precipitates in PbTe . The evidence is derived from two experimental findings: (i) as illustrated in Figure S6b, the Hall coefficients of Cu-containing samples start to upturn around 608 K, indicative of reduced p H most probably by increasing interstitial Cu atoms and (ii) the thermal expansion coefficient (TEC) of the x = 0.01 sample starts to rapidly climb up at ∼600 K, while no such abnormality is observed in Pb 0.98 Na 0.02 Se, as seen in Figure d.…”

Section: Resultsmentioning

confidence: 89%

Defect Chemistry Engineering Promotes the Dopability of Cu for an Extraordinary Thermoelectric Performance of Hole-Doped PbSe with Resonant States

et al. 2023

View full text Add to dashboard Cite

Cu substitution for Pb (Cu Pb ) has been theoretically predicted to introduce resonant states near the valence band edge of PbSe. However, experimentally, it has not been verified yet due to the extremely low solubility (∼0.3 atom %) of Cu Pb . In this study, we demonstrate that the solubility limit of Cu Pb is extended to at least 1.5 atom % in PbSe by pairing with an identical amount of Cu interstitials (Cu i ), while excess Cu precipitates out as a Cu 2 Se phase at grain boundaries. As a result of the increased dopability of Cu Pb , a significant enhancement of the Seebeck coefficient is realized in hole-doped PbSe because of Cu Pb -induced resonant states. This is also testified by first-principles calculations. Moreover, the rich point defects (Cu Pb , Cu i ), line defects (dislocations), and Cu 2 Se precipitates remarkably frustrate the phonon propagation of PbSe, leading to ∼45% reduction of lattice thermal conductivity (κ lat ) at room temperature. At elevated temperatures (>623 K), there is a dynamic migration of Cu atoms from Cu 2 Se precipitates to tetrahedral interstices of the PbSe matrix as evidenced by the temperature-variant Hall study and thermal expansion coefficient measurement. This diffusion-like process of Cu further drops the κ lat to ∼0.27 W m −1 K −1 at 823 K. Consequently, a peak ZT of ∼1.8 at 873 K is achieved in the (Cu i ) 0.01 Pb 0.97 (Cu Pb ) 0.01 Na 0.02 Se sample. This work highlights the potential of the defect structure design in innovating new functional materials, particularly high-performance thermoelectrics.

show abstract

“…1. The potential of this approach is exemplified by Ag-doped PbTe, a typical thermoelectric material used for power generation 25 . Electron backscattered diffraction (EBSD) will be utilized to characterize the orientation of different grains and the classification of GBs, e.g., LAGBs and high-angle GBs (HAGBs) (Fig.…”

Section: Correlative Microscopy and Characterizationmentioning

confidence: 99%

“…In this work, we choose Ag as the dopant because it has been widely used in thermoelectrics and it can often decorate GBs, which is important for the visualization of different GB features in the APT results. The content of Ag should be low (PbTe-0.005 Ag) to avoid the formation of complex structural defects and second-phase precipitates at GBs 25 .…”

Section: Synthesismentioning

confidence: 99%

Strong charge carrier scattering at grain boundaries of PbTe caused by the collapse of metavalent bonding

et al. 2023

Nat Commun

Self Cite

View full text Add to dashboard Cite

Grain boundaries (GBs) play a significant role in controlling the transport of mass, heat and charge. To unravel the mechanisms underpinning the charge carrier scattering at GBs, correlative microscopy combined with local transport measurements is realized. For the PbTe material, the strength of carrier scattering at GBs depends on its misorientation angle. A concomitant change in the barrier height is observed, significantly increasing from low- to high-angle GBs. Atom probe tomography measurements reveal a disruption of metavalent bonding (MVB) at the dislocation cores of low-angle GBs, as evidenced by the abrupt change in bond-rupture behavior. In contrast, MVB is completely destroyed at high-angle GBs, presumably due to the increased Peierls distortion. The collapse of MVB is accompanied by a breakdown of the dielectric screening, which explains the enlarged GB barrier height. These findings correlate charge carrier scattering with bonding locally, promising new avenues for the design of advanced functional materials.

show abstract

Dynamic doping and Cottrell atmosphere optimize the thermoelectric performance of n-type PbTe over a broad temperature interval

Cited by 24 publications

References 59 publications

Grain Boundary Complexions Enable a Simultaneous Optimization of Electron and Phonon Transport Leading to High‐Performance GeTe Thermoelectric Devices

Grain Boundary Complexions Enable a Simultaneous Optimization of Electron and Phonon Transport Leading to High‐Performance GeTe Thermoelectric Devices

Defect Chemistry Engineering Promotes the Dopability of Cu for an Extraordinary Thermoelectric Performance of Hole-Doped PbSe with Resonant States

Strong charge carrier scattering at grain boundaries of PbTe caused by the collapse of metavalent bonding

Contact Info

Product

Resources

About