Search

SnTe is a lead-free and promising p-type thermoelectric material in an intermediate temperature range (500–900 K), but its intrinsic performance is poor due to excess cation vacancies and relativel...

To realize the widespread use of thermoelectric (TE) applications, developing low-cost, eco-friendly, and high-performance TE materials with an optimal band gap is essential. We find that the lapie...

The argyrodite compound, Ag8SnSe6 (ATS), which is one of the promising thermoelectric (TE) candidates, is receiving growing attention in thermoelectrics recently. However, its TE performance is sti...

Thermoelectric properties of CoSb3-based skutterudites are greatly determined by the removal of detrimental impurities, such as (Fe/Co)Sb2, (Fe/Co)Sb, and Sb. In this study, we use a facile temperature gradient zone melting (TGZM) method to synthesize high-performance CoSb3-based skutterudites by impurity removal. After removing metallic or semimetallic impurities (Fe/Co)Sb, (Fe/Co)Sb2, and Sb, the carrier concentration of TGZM-Ce0.75Fe3CoSb12 can be reduced to 1.21 × 1020 cm-3 and the electronic thermal conductivity dramatically reduced to 0.7 W m-1 K-1 at 693 K. Additionally, removing these impurities also effectively reduces the lattice thermal conductivity from 7.2 W m-1 K-1 of cast-Ce0.75Fe3CoSb12 to 1.02 W m-1 K-1 of TGZM-Ce0.75Fe3CoSb12 at 693 K. As a consequence, TGZM-Ce0.75Fe3CoSb12 approaches a high power factor of 11.7 μW cm-1 K-2 and low thermal conductivity of 1.72 W m-1 K-1 at 693 K, leading to a peak zT of 0.48 at 693 K, which is 10 times higher than that of cast-Ce0.75Fe3CoSb12. This study indicates that our facile TGZM method can effectively synthesize high-performance CoSb3-based skutterudites by impurity removal and set up a solid foundation for further development.

Polycrystalline SnSe materials with ZT values comparable to those of SnSe crystals are greatly desired due to facile processing, machinability, and scale-up application. Here manipulating interatom...

Low-dimensional materials attract extensive interest in electronic applications since the synthesis of graphene. Understanding the thermal transport in low-dimensional materials with shrinking char...

In this work, we have improved the thermoelectric performance of n-type AgBiSe2 by engineering its chemical compositions. This engineering is realized by doping Ag2Se at first and then In and S in ...

Understanding the origin of intrinsic lattice thermal conductivity in crystalline solids is critical to research fields ranging from thermoelectric materials to thermal barrier coatings. This work ...

The simultaneous reduction of the lattice thermal conductivity and maintenance of the electrical conductivity are great challenges for porous thermoelectric materials in achieving superior thermoel...

As the development of n-type ternary chalcopyrite semiconductors in thermoelectrics (TEs) is relatively slow compared to that of their p-type counterparts, it greatly restricts the fabrication of t...

We report first-principle calculations of the recently synthesized Pb-free double perovskite Cs2PtI6, which we found to have the potential to be an excellent thermoelectric material, through the in...

For efficient thermoelectric materials, high power factor and low lattice thermal conductivity are desired properties. Therefore, the high lattice thermal conductivity of two-dimensional materials ...

The presence of lone-pair electrons (LPE) is known to lead to large anharmonicities in materials and thus to low lattice thermal conductivity (κ). Materials with LPE typically have κ values that ar...

SnTe is proposed to be one intriguing low-toxicity alternative to PbTe. Herein, we report the diminished lattice thermal conductivity (κL) and enhanced zT of SnTe by way of vacancy engineering. (Sn...

In this work, we report a series of Cu3RTe3 (R = Y, Sm, and Dy) ternary compounds with a trigonal structure (R3) as a family of new thermoelectric materials. First-principles calculations show tha...

To recover the low-grade waste heat (300-500 K), it is of urgent importance to develop and improve the thermoelectric performance at a low-temperature region. Herein, we have realized a record high ZT value of 1.4 at 410 K and a record high average ZT value of 0.6 in the temperature interval from 300 to 400 K for Sb-doped Ag2SbxTe1-x (x = 0-0.03) compounds, which show an improvement of 180 and 120% compared to pristine Ag2Te, respectively. Sb doping increases the carrier concentration and electrical conductivity, leading to a remarkable improvement of electrical transport properties. The Ag2Sb0.015Te0.985 sample obtains the maximal power factor of 1.07 × 10-3 W m-1 K-2 at 410 K, which is increased by 80% in comparison to that of pristine Ag2Te. Moreover, as a result of the intensified alloying phonon scattering by Sb doping, Ag2Sb0.01Te0.99 possesses the minimum lattice thermal conductivity of 0.35 W m-1 K-1 at 300 K, which demonstrates a decline of 57% compared to that of pristine Ag2Te. All of these produce a great enhancement on the thermoelectric performance of Ag2Te materials, which shows great potential in the application of recycling the low-grade waste heat at a low-temperature region.

Single crystals of tin selenide (SnSe), a layered material, have recently drawn massive attention in the field of thermoelectrics for its low thermal conductivity and high thermoelectric figure of ...

Zintl phases are excellent candidates for high-efficiency thermoelectrics (TEs) due to their extremely low lattice thermal conductivity. The manufacturing of an all-Zintl module is particularly att...

The superior performance of GeTe-based materials has drawn increased attention in the community of thermoelectrics. Originating mainly from the low lattice thermal conductivity (κl) caused by vast ...

Ag-based argyrodites with a general formula of Ag(12–n)Bn+X6 (B = Ga/Al/Si/Ge/Sn and X = S/Se/Te) have recently attracted much attention as promising thermoelectrics because of their ultralow latti...

Although Sb doping is regarded as the most effective method to regulate the carrier concentration within the optimum range for ZrNiSn-based half-Heusler (HH) alloys, the resulting thermal conductiv...

In this work, A2Cu3In3Te8 (A = Cd, Zn, Mn, Mg) thermoelectric chalcogenide materials, exhibiting intrinsically complex structures, low lattice thermal conductivities, high Seebeck coefficients, and...

Eco-friendly and low-cost layered SnSe2-based materials have been attracting great attention in the thermoelectric field for their intrinsically low thermal conductivity. In this work, we applied A...

In recent years, the layered semiconductor tin selenide (SnSe) has been of great interest in the thermoelectric field because of its remarkable thermoelectric potential. Here, the as-grown Sn0.98Se...

To date, thermoelectric performance has been enhanced through improving the power factor and/or reducing the lattice thermal conductivity. Here, we report an effective method of boosting thermoelec...

As an inexpensive and earth abundant analogue of PbTe, PbSe has aroused growing attention recently as advanced thermoelectric materials. In the present report, the effect of PbTe and PbS co-alloyin...

The ternary chalcopyrite AgInSe2 has emerged as a promising n-type thermoelectric material with ultralow lattice thermal conductivity. We report the thermoelectric transport properties of sodium-do...

β-FeSi2 has been considered a promising material for thermoelectric applications, but its thermoelectric performance is greatly limited by the overhigh lattice thermal conductivity. In thermoelectrics, alloying an effective method to reduce the lattice thermal conductivity. In this study, we chose the Co-doped β-FeSi2 (Fe0.94Co0.06Si2) as the matrix and then prepared a series of Ru alloyed Fe0.94-xRuxCo0.06Si2 (x = 0, 0.005, 0.01, 0.02, and 0.05). X-ray characterizations show that all samples crystallize in the β-FeSi2 structure. The elemental mappings detect an inhomogeneous Ru distribution in Fe0.89Ru0.05Co0.06Si2, which is attributed to the different Ru solution contents in e-FeSi and α-FeSi2+δ before the formation of β-FeSi2 and the slow diffusion behavior of Ru during the annealing process. The Ru-alloying obviously reduces the lattice thermal conductivity via introducing the mass and strain field fluctuations to interrupt the phonon transports, while it has a weak effect on electrical transport properties. Finally, a maximum zT value of 0.33 at 900 K has been obtained for Fe0.89Ru0.05Co0.06Si2, which is about 27% higher than that for Fe0.94Co0.06Si2.

Elemental tellurium exhibits a promising thermoelectric performance, largely due to the optimization of the carrier concentration stemming from effective chemical doping. In this study, we demonstr...

As an environment-friendly alternative to traditional PbTe, many attempts have recently been made to improve thermoelectric SnTe. Effective strategies are mainly focused on valence band convergence, nanostructuring, interstitial defects, and alloying solubility. In particular, alloying SnTe with CdTe/GeTe triggers an inherent decline of valence band offset effectively owing to a high solubility of ∼20% of CdTe. However, to what level an additional element doping in low-solubility SnTe-CdTe alloys can play a role in enhancing the thermoelectric performance still remains a mystery. Here, a new strategy is shown that unexpected Bi doping, by alloying with only ∼3% CdTe, induces a significant enhancement of the thermoelectric figure of merit ZT to be ∼240% (ZT up to ∼1.3) at 838 K, which is mainly determined by the dramatically reduced lattice thermal conductivity above 800 K deriving from the exotic Bi doping and Cu-interstitial defects. More interestingly, combining experimental and theoretical evidences, the Bi-doping-driven band convergence is also beneficial to the improvement of thermoelectric performance below 800 K. The present findings demonstrate the extraordinary role of Bi for advancing the thermoelectric performance in SnTe alloys.

In thermoelectric research, the introduction of a dopant can suppress lattice thermal conductivity (κ1) through phonon scattering and optimize the power factor (PF) by changing the behavior of carr...

Although introducing more fillers in nanocages is beneficial to gain low lattice thermal conductivity within filling fraction limit, accompanying high electronic thermal conductivity usually results in an unsatisfactory figure of merit

SnTe has been regarded as an environment-friendly alternative of PbTe thermoelectrics, although its performance is limited by its high thermal conductivity, partly owing to its high carrier concent...

We investigated the lattice thermal conductivity (LTC) of a subset of polymer crystals from the polymer genome library to explore high LTC polymer systems. We employed a first-principles approach t...

An efficient technique to prepare high-ZT skutterudites is described. Nearly single-phase Te-doped CoSb3–xTex ingots are synthesized by microwave processing for 5 min, and materials with 98% relati...

In most materials the electron–phonon (e-p) scattering is far weaker than phonon–phonon (p-p) scattering, and the e-p scattering is usually proportional to the e-p coupling strength. Here, we repor...

SnSe-based materials possess ultrahigh thermoelectric efficiency and show great potential in next-generation thermoelectric devices. The excellent thermoelectric performance of SnSe has been attrib...

Six new quaternary chalcogenides belonging to the pavonite sulfosalt mineral family with the general formula Mn+1(Bi/Sb)2Qn+5 (n = 2–7) were synthesized by direct reactions of the elements at high ...

Recently, polycrystalline argyrodite Ag8SnSe6 has shown promising thermoelectric performance, which largely relies on the ultralow lattice thermal conductivity. However, the thermoelectric properti...

Due to their thermoelectric properties, intermetallic clathrates are technologically highly interesting materials. Especially their strongly reduced lattice thermal conductivity has been largely investigated and strongly debated. Although density-functional-theory-based lattice dynamics calculations have helped clarify the thermal transport in clathrates, significant discrepancies remain between experiment and theory, especially in Ge-based clathrates. In this work, we show that the recently released meta-generalized-gradient approximation functional SCAN (strongly constrained and appropriately normed) is able to overcome these issues and provide a much improved agreement between the experimental and the theoretical phonon spectra, thus enabling quantitative predictions of the clathrate phases with a high potential for thermoelectric applications.

Thermal conductivity is an important physical parameter for the application of nonlinear optical single crystal materials. The underlying science of thermal transport behavior is not well establish...

The ZrNiSn-based half-Heusler compounds are promising for thermoelectric applications in the mid-to-high temperature range. However, their thermoelectric performance was greatly limited due to the remaining high thermal conductivity, especially the lattice thermal conductivity. Herein, we report the synthesis of pristine half-Heusler ZrNiSn through direct mechanical alloying at a liquid nitrogen temperature (i.e., cryomilling) followed by spark plasma sintering. It is shown that the onset sintering temperature is greatly reduced for the cryomilled powders with a high density. A reduced thermal conductivity is subsequently realized from room temperature to 700 °C in the cryomilled samples than the one that was differently prepared (from 7.3 to 4.5 W/m K at room temperature). The pronounced reduction in thermal conductivity of ZrNiSn yields a maximum zT of ∼0.65 at 700 °C. Our study shows the possibility of cryomilling in advancing the thermoelectric performance through enhanced phonon scattering.

The last two decades have seen tremendous progress in quantitative understanding of several major phonon scattering mechanisms (phonon-phonon, phonon-boundary, phonon-defects), as they are the determinant factors in lattice thermal transport, which is critical for the proper functioning of various electronic and energy conversion devices. However, the roles of another major scattering mechanism, electron-phonon (e-ph) interactions, remain elusive. This is largely due to the lack of solid experimental evidence for the effects of e-ph scattering in the lattice thermal conductivity for the material systems studied thus far. Here we show distinct signatures in the lattice thermal conductivity observed below the charge density wave transition temperatures in NbSe3 nanowires, which cannot be recaptured without considering e-ph scattering. Our findings can serve as the cornerstone for quantitative understanding of the e-ph scattering effects on lattice thermal transport in many technologically important materials.

Superionic argyrodites have been identified as thermoelectric materials with inherent ultralow lattice thermal conductivity because of liquid-like behavior of cations in a relatively larger unit ce...

We survey the thermodynamic stabilities and properties, electronic transports, and thermoelectric possibilities of two-dimensional (2D) ZnPS3 and ZnPSe3, belonging to transition-metal phosphorus trichalcogenides, by employing the first-principles electronic structure calculation. Our first-principles calculation accompanying ab initio molecular dynamics and phonon calculation predicts that a single-layer (1L-) ZnPSe3 would be thermodynamically stable; in addition, electron and hole mobilities of 1L-ZnPSe3 amount to ∼440 and ∼400 cm2 V–1 s–1, respectively, which are comparable to 1L-MoS2. More interestingly, the lattice thermal conductivity of 1L-ZnPSe3 is found to be lower than any other 2D material, which could reach the lowest, i.e., ∼0.13 W m–1 K–1 at room temperature. In contrast, the thermoelectric figure of merit of the pristine 1L-ZnPSe3 is just ∼0.8 under optimal condition. Nevertheless, this is a very promising indication for a thermoelectric application of 1L-ZnPSe3 because other elements to det...

Band convergence has been proven as an effective approach for enhancing thermoelectric performance, particularly in p-type IV–VI semiconductors, where the superior electronic performance originates...

Much effort has recently been directed at advancing thermoelectric SnTe as an alternative to PbTe. Effective methods include energy band convergence, nanostructures, and substitutional and interstitial defects. Among these strategies, it is shown that CdTe alloying effectively reduces the energy offset between valence bands for an enhanced thermoelectric figure of merit, zT. However, its solubility of only ∼6% might limit this effect on a full zT optimization in SnTe–CdTe alloys. Here, we show an effective approach for increasing CdTe solubility up to ∼20%, with the help of the existence of 5% GeTe. This leads the valence bands to be further converged for improving electronic performance. In addition, Cu2Te alloying is used to create interstitial defects for reducing the lattice thermal conductivity. Eventually, the increase of CdTe solubility and the creation of Cu interstitials enable a significantly enhanced zT, indicating the importance of solubility manipulation for engineering the band structure in ...