Controlled Phonon Transport via Chemical Bond Stretching and Defect Engineering: The Case Study of Filled β-Mn-Type Phases.

Controlling the elastic properties of the material could become a powerful tool for tuning the thermal transport in solids. Nevertheless, the impact of the crystal structure, chemical bonding, and elastic properties on the lattice thermal conductivity remains to be elucidated. This is a pivotal issue for the advancement of thermoelectric (TE) materials.

Achieving high thermoelectric conversion efficiency in BiTe-based stepwise legs through bandgap tuning and chemical potential engineering.

In this study, we show that the energy conversion efficiency in thermoelectric (TE) devices can be effectively improved through simultaneous optimization of carrier concentration, bandgap tuning, and fabrication of stepwise legs. - and -type BiTe-based materials were selected as examples for testing the proposed approach. At first, the Boltzmann transport theory was employed to predict the optimal temperature-dependent carrier concentration for high thermoelectric performance over a broad temperature range.

Structure Evolution and Bonding Inhomogeneity toward High Thermoelectric Performance in CuCoSnSSe Materials.

Lightweight diamond-like structure (DLS) materials are excellent candidates for thermoelectric (TE) applications due to their low costs, eco-friendly nature, and property stability. The main obstacles restricting the energy-conversion performance by the lightweight DLS materials are high lattice thermal conductivity and relatively low carrier mobility. By investigating the anion substitution effect on the structural, microstructural, electronic, and thermal properties of CuCoSnSSe, we show that the simultaneous enhancement of the crystal symmetry and bonding inhomogeneity engineering are effective approaches to enhance the TE performance in lightweight DLS materials.

Synergistic Effect of Work Function and Acoustic Impedance Mismatch for Improved Thermoelectric Performance in GeTe-WC Composite.

The preparation of composite materials is a promising methodology for concurrent optimization of electrical and thermal transport properties for improved thermoelectric (TE) performance. This study demonstrates how the acoustic impedance mismatch (AIM) and the work function of components decouple the TE parameters to achieve enhanced TE performance of the (1-)GeMnSbTe-()WC composite. The simultaneous increase in the electrical conductivity (σ) and Seebeck coefficient (α) with WC (tungsten carbide) volume fraction () results in an enhanced power factor (ασ) in the composite.

Lone-Pair-Like Interaction and Bonding Inhomogeneity Induce Ultralow Lattice Thermal Conductivity in Filled β-Manganese-Type Phases.

Finding a way to interlink heat transport with the crystal structure and order/disorder phenomena is crucial for designing materials with ultralow lattice thermal conductivity. Here, we revisit the crystal structure and explore the thermoelectric properties of several compounds from the family of the filled β-Mn-type phases GaTe ( = Pb, Sn, Ca, Na, Na + Ag). The strongly disturbed thermal transport observed in the investigated materials originates from a three-dimensional Te-Ga network with lone-pair-like interactions, which results in large variations of the Ga-Te and -Te interatomic distances and substantial anharmonic effects.

Ultralow Lattice Thermal Conductivity and Improved Thermoelectric Performance in Cl-Doped BiTeSe Alloys.

BiTe-based alloys are the main materials for the construction of low- and medium-temperature thermoelectric modules. In this work, the microstructure and thermoelectric properties of Cl-doped BiTeSe alloys were systematically investigated considering the high anisotropy inherent in these materials. The prepared samples have a highly oriented microstructure morphology, which results in very different thermal transport properties in two pressing directions.

Crystal Structure and Thermoelectric Properties of Novel Quaternary CuMHfS (M-Mn, Fe, Co, and Ni) Thiospinels with Low Thermal Conductivity.

Uncovering of the origin of intrinsically low thermal conductivity in novel crystalline solids is among the main streams in modern thermoelectricity. Because of their earth-abundant nature and environmentally friendly content, Cu-based thiospinels are attractive functional semiconductors, including thermoelectric (TE) materials. Herein, we report the crystal structure, as well as electronic and TE properties of four new CuMHfS (M-Mn, Fe, Co, and Ni) thiospinels.

Phase Analysis and Thermoelectric Properties of Cu-Rich Tetrahedrite Prepared by Solvothermal Synthesis.

Because of the large Seebeck coefficient, low thermal conductivity, and earth-abundant nature of components, tetrahedrites are promising thermoelectric materials. DFT calculations reveal that the additional copper atoms in Cu-rich CuSbS tetrahedrite can effectively engineer the chemical potential towards high thermoelectric performance. Here, the Cu-rich tetrahedrite phase was prepared using a novel approach, which is based on the solvothermal method and piperazine serving both as solvent and reagent.

High Thermoelectric Performance of -Type PbTe Enabled by the Synergy of Resonance Scattering and Lattice Softening.

In this work, we show the simultaneous enhancement of electrical transport and reduction of phonon propagation in -type PbTe codoped with Tl and Na. The effective use of advanced electronic structure engineering improves the thermoelectric power factor σ over the temperature range from 300 to 825 K. A rise in the Seebeck coefficient was obtained due to the enhanced effective mass *, coming from the Tl resonance state in PbTe.

Entropy-Induced Multivalley Band Structures Improve Thermoelectric Performance in -CuP(SSe) Argyrodites.

Searching for novel low-cost and eco-friendly materials for energy conversion is a good way to provide widespread utilization of thermoelectric technologies. Herein, we report the thermal behavior, phase equilibria data, and thermoelectric properties for the promising argyrodite-based CuP(SSe) thermoelectrics. Alloying of CuPSe with CuPS provides a continuous solid solution over the whole compositional range, as shown in the proposed phase diagram for the CuPS-CuPSe system.

Origins of low lattice thermal conductivity of PbSnTe alloys for thermoelectric applications.

Lead telluride is a well-established material for direct conversion of heat into electricity. However, the aspects of the heat transport phenomena for PbTe-alloys remain not fully understood. Here, for the first time, origins of the phonon scattering in PbSnTe compounds were studied through changes in the effective anharmonic pair potential obtained from X-ray Absorption Fine Structure (XAFS) spectroscopy.

Phase Equilibria and Thermoelectric Properties in the Pb-Ga-Te System in the Vicinity of the PbGaTe Phase.

PbGaTe is a promising thermoelectric (TE) material due to its ultralow thermal conductivity and moderated values of the Seebeck coefficient. However, the reproducible synthesis of the PbGaTe-based materials for the investigation and tailoring of physical properties requires detailed knowledge of the phase diagram of the system. With this aim, a combined thermal, structural, and microstructural study of the Pb-Ga-Te ternary system near the PbGaTe composition is presented here, in which polycrystalline samples with the compositions (PbTe)(GaTe) (0.

Thermal conductivity of PbTe-CoSb bulk polycrystalline composite: role of microstructure and interface thermal resistance.

Systematic experimental and theoretical research on the role of microstructure and interface thermal resistance on the thermal conductivity of the PbTe-CoSb3 bulk polycrystalline composite is presented. In particular, the correlation between the particle size of the dispersed phase and interface thermal resistance (Rint) on the phonon thermal conductivity (κph) is discussed. With this aim, a series of PbTe-CoSb3 polycrystalline composite materials with different particle sizes of CoSb3 was prepared.