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A comparison of the thermoelectric performance and compatibility between the composite in this study and other state-of-art IV–VI compounds.

A recent discovery of high-performance Mg3Sb2 has ignited tremendous research activities in searching for novel Zintl-phase compounds as promising thermoelectric materials. Herein, a series of planar Zintl-phase XCuSb (X = Ca, Sr, Ba) thermoelectric materials are developed by vacuum induction melting. All these compounds exhibit high carrier mobilities and intrinsic low lattice thermal conductivities (below 1 W·m−1·K−1 at 1010 K), resulting in peak p-type zT values of 0.14, 0.30, and 0.48 for CaCuSb, SrCuSb, and BaCuSb, respectively. By using BaCuSb as a prototypical example, the origins of low lattice thermal conductivity are attributed to the strong interlayer vibrational anharmonicity of Cu—Sb honeycomb sublattice. Moreover, the first-principles calculations reveal that n-type BaCuSb can achieve superior thermoelectric performance with the peak zT beyond 1.1 because of larger conducting band degeneracy. This work sheds light on the high-temperature thermoelectric potential of planar Zintl compounds, thereby stimulating intense interest in the investigation of this unexplored material family for higher zT values.

Na2S and Si alloying synergistically optimizes the electrical and thermal transport properties of melt-spun p-type Mg2Sn, contributing to a peak thermoelectric zT of 0.52 at 723 K.

Thermoelectric materials are typically highly degenerate semiconductors, which require high carrier concentration. However, the efficiency of conventional doping by replacing host atoms with alien ones is restricted by solubility limit, and, more unfavorably, such a doping method is likely to cause strong charge-carrier scattering at ambient temperature, leading to deteriorated electrical performance. Here, an unconventional doping strategy is proposed, where a small trace of alien atoms is used to stabilize cation vacancies in Cu

Quasi-two-dimensional (quasi-2D) semiconductors have garnered immense research interest for next-generation electronics and thermoelectrics due to their unique structural, mechanical, and transport properties. However, most quasi-2D semiconductors experimentally synthesized so far have relatively low carrier mobility, preventing the achievement of exceptional power output. To break through this obstacle, we propose a route based on the crystal symmetry arguments to facilitate the charge transport of quasi-2D semiconductors, in which the horizontal mirror symmetry is found to vanish the electron-phonon coupling strength mediated by phonons with purely out-of-plane vibrational vectors. This is demonstrated in ZrBeSi-type quasi-2D systems, where the representative sample Ba

Here, we report the thermal transport properties of lead telluride (PbTe)1− x(AgBiTe2) x ( x = 0.05 and 0.15) alloys. It is found that the prominent peak in lattice thermal conductivity at 15 K for PbTe disappears after forming solid solution with AgBiTe2, exhibiting a typical glass-like thermal transport behavior. The high energy phonons are scattered by the point defects induced by cationic disorder, while the appearance of soft vibrational modes arises from Ag atoms acting like Einstein oscillators ( ΘE1 = 5.4 K, ΘE2 = 67.3 K), which substantially affects the lattice thermal conductivity. Further with nanostructuring, the mid-frequency phonons are scattered by the high-density disc-like Ag2Te precipitates. As a result, an ultralow lattice thermal conductivity (≤1.0 W m−1 K−1) for (PbTe)0.85(AgBiTe2)0.15 is obtained, which is the lowest value ever reported to date for the PbTe-based TE materials. Our work highlights a synthetic route to achieve glass-like lattice thermal conductivity in PbTe over the entire temperature range.

Mg3Sb2 has attracted intensive attention as a typical Zintl-type thermoelectric material. Despite the exceptional thermoelectric performance in n-type Mg3Sb2, the dimensionless figure of merit (zT) of p-type Mg3Sb2 remains lower than 1, which is mainly attributed to its inferior electrical properties. Herein, we synergistically optimize the thermoelectric properties of p-type Mg3Sb2 materials via codoping of Cd and Ag, which were synthesized by high-energy ball milling combined with hot pressing. It is found that Cd doping not only increases the carrier mobility of p-type Mg3Sb2, but also diminishes its thermal conductivity (κtot), with Mg2.85Cd0.5Sb2 achieving a low κtot value of ∼0.67 W m−1 K−1 at room temperature. Further Ag doping elevates the carrier concentration, so that the power factor is optimized over the entire temperature range. Eventually, a peak zT of ∼0.75 at 773 K and an excellent average zT of ∼0.41 over 300 − 773 K are obtained in Mg2.82Ag0.03Cd0.5Sb2, which are ∼240% and ∼490% higher than those of pristine Mg3.4Sb2, respectively. This study provides an effective pathway to synergistically improve the thermoelectric performance of p-type Mg3Sb2 by codoping Cd and Ag, which is beneficial to the future applications of Mg3Sb2-based thermoelectric materials.

Bornite (Cu

The suppression of lattice thermal conductivity of thermoelectric CuInTe2 was often realized by complex micrometer-structure control. Herein, we demonstrate that simple alloying AgSbTe2 in CuInTe2 is capable of strongly strengthening lattice anharmonicity, which gives rise to an extremely low lattice thermal conductivity of ∼ 0.62 W m−1 K−1 at 823 K for (CuInTe2)0.95(AgSbTe2)0.05. In addition, the intentionally introduced copper vacancies can effectively increase the carrier concentration and dramatically improve the electrical performance of (CuInTe2)0.95(AgSbTe2)0.05. As a result, the sample with nominal composition of (Cu0.95InTe2)0.95(AgSbTe2)0.05 reaches a maximum zT value of ∼ 1.3 at 823 K. This study provides some insight into designing thermoelectric compounds in the diamond-like semiconductor family by inducing strong anharmonicity through a small amount of alloying.

The authors of the article entitled 'Super Deformable Behavior in Layered Structure InSe Single Crystals' found that the strain calculation is incorrect in the Mechanical Analysis section. Consequently, this paper has been withdrawn from publication.

Bornite (Cu5 FeS4 ) is an Earth-abundant, nontoxic thermoelectric material. Herein, twin engineering and Se alloying are combined in order to further improve its thermoelectric performance. Cu5 FeS4-x Sex (0 ≤ x ≤ 0.4) icosahedral nanoparticles, containing high-density twin boundaries, have been synthesized by a colloidal method. Spark plasma sintering retains twin boundaries in the pellets sintered from Cu5 FeS4-x Sex colloidal powders. Thermoelectric property measurement demonstrates that alloying Se increases the carrier concentration, leading to much-improved power factor in Se-substituted Cu5 FeS4 , for example, 0.84 mW m-1 K-2 at 726 K for Cu5 FeS3.6 Se0.4 ; low lattice thermal conductivity is also achieved, due to intrinsic structural complexity, distorted crystal structure, and existing twin boundaries and point defects. As a result, a maximum zT of 0.75 is attained for Cu5 FeS3.6 Se0.4 at 726 K, which is about 23% higher than that of Cu5 FeS4 and compares favorably to that of reported Cu5 FeS4 -based materials. In addition, the Cu5 FeS4-x Sex samples containing twin boundaries also obtain improved hardness compared to the ones fabricated by melting-annealing or ball milling. This work demonstrates an effective twin engineering-composition tuning strategy toward enhanced thermoelectric and mechanical properties of Cu5 FeS4 -based materials.

AgBiSe2 is a promising n-type compound with high thermoelectric performance but suffers from a multiple structural phase transition. Here, we show the high-temperature rock salt phase can be stabilized at ambient conditions in AgBi1-xSbxSe2 solid solutions with x higher than 0.2, which is attributed to the increased configurational entropy. Moreover, the optimum increment of configurational entropy is determined by analyzing the weighted mobility and quality factor. Finally, benefiting from the intrinsically low lattice thermal conductivity and well-maintained carrier mobility, a peak zT value of 0.86 at 790 K, is attained for cubic AgBi0.8Sb0.2Se2 after bromine doping. This work highlights the importance of entropy engineering in thermoelectric performance and phase stability, providing insights into the discovery and design of environmental-friendly thermoelectrics.

Indium selenide, a III–V group semiconductor with layered structure, attracts intense attention in various photoelectric applications, due to its outstanding properties. Here, we report super deformability and thermoelectricity of γ-InSe single crystals grown by modified Bridgeman method. The crystal structure of InSe is studied systematically by transmission electron microscopy methods combined with x-ray diffraction and Raman spectroscopy. The predominate phase of γ-InSe with dense stacking faults and local multiphases is directly demonstrated at atomic scale. The bulk γ-InSe crystals demonstrate surprisingly high intrinsic super deformative ability which is highly pliable with bending strains exceeding 12.5% and 264% extension by rolling. At the meantime, InSe also possesses graphite-like features which is printable, writable, and erasable. Finally, the thermoelectric properties of γ-InSe bulk single crystals are preliminary studied and thermal conductivity can be further reduced via bending-induced defects. These findings will enrich the knowledge of structural and mechanical properties’ flexibility of InSe and shed lights on the intrinsic and unique mechanical properties of InSe polytypes.

SnTe has attracted worldwide attention as a non-toxic candidate material for thermoelectric applications; however, un-modified SnTe possesses inferior thermoelectric properties. Herein, we report the significantly improved thermoelectric performance in Sb, Mn-codoped SnTe synthesized by energy-efficient melt spinning. Sb segregation was observed at the grain boundaries of Sb-doped and Sb, Mn-codoped SnTe melt-spun ribbons, leading to grain refinement; subsequent sintering promotes the diffusion of Sb while retains Sb-rich particles. Initially, intensified phonon scattering from unique multiscale microstructures, including point defects, Sb-rich particles and high-density dislocations generated after Sb doping, effectively diminishes the lattice thermal conductivity of SnTe, leading to a substantially low value of 0.55 W m−1 K−1 in Sn0.84Sb0.16Te at 300 K. Further, the power factors are significantly enhanced via Mn doping owing to valence band convergence, verified by first-principles calculation. Consequently, a peak zT of ~ 1.27 at 773 K and an exceptional average zT of ~ 0.89 over 300–873 K are obtained in Sn0.72Sb0.16Mn0.12Te, which are ~ 110% and ~ 340% higher than those of SnTe, respectively. This study provides an effective pathway to synergistically improve the thermoelectric performance of SnTe by microstructure and band structure engineering, and establishes melt spinning as a controllable synthetic method to high-performance thermoelectrics.