α-MgAgSb is an environmentally friendly alternative to traditional tellurium-based thermoelectric materials for near room temperature applications. In this study, we enhance the thermoelectric properties of α-MgAgSb by introducing a secondary Sb2Te3 phase using powder atomic layer deposition (powder ALD), with the aim to modify phonon scattering mechanisms and reduce the lattice thermal conductivity. Powder ALD is a thin-film deposition technique that allows for the deposition of self-limiting monolayers on high aspect ratio surfaces, enabling the conformal coating of nanopowder regardless of particle morphology. Sb2Te3 was selected as the coating material due to its oxygen-free synthesis route and its potential for good interfacial compatibility with the α-MgAgSb powders. Our results reveal a 10% decrease in lattice thermal conductivity of bulk α-MgAgSb as the powder ALD coating thickness increases from pristine to 20 cycles of Sb2Te3, without affecting the primary phase purity. Our findings highlight the effectiveness of nonoxide powder ALD coatings in suppressing lattice thermal transport, offering a promising pathway for interface-engineered, low-toxicity thermoelectric materials.

NbFeSb-based half-Heusler alloys offer high electrical conductivity and mechanical strength, yet suffer from high lattice thermal conductivity. Constructing complex microstructures to reduce thermal conductivity remains challenging due to high-temperature processing. This study introduces PbI2 during ball-milling, which sublimates during sintering, creating a hierarchical structure in Nb0.8Ti0.2FeSb. The resulting features-PbI2 nanophases, core-shell pore@Pb structures, multiscale porosity, and Fe vacancies-enable full-spectrum phonon scattering. Furthermore, the presence of Fe vacancies softens the lattice and reduces the sound velocity. Together, these reduce lattice thermal conductivity to 3.34W m-1 K-1 at 973 K, a 32% decrease. Lowered grain-boundary barriers reduce hole trapping, increasing carrier concentration and electrical conductivity, leading to a power factor of 52.7 µW cm-1 K-2 and zT ~ 1. The material maintains high compressive strength (1132MPa, 38% improvement) and microhardness (950 HV), as second-phase strengthening offsets pore-induced weakening. This approach demonstrates that sublimable compounds can form full-scale hierarchical architectures in high-temperature thermoelectrics, enabling both robust mechanical and thermoelectric performance.

Thermoelectric materials enable the conversion of heat into electricity with no waste heat. Nanotwined AgMnGePbSbTe5, a novel P-type narrow bandgap high-entropy semiconductor, exhibits enhanced thermoelectric performance upon the introduction of Pb vacancies. With increasing Pb vacancy content, the hole concentration rose monotonically, dramatically augmenting the electrical conductivity, thus enhancing the power factor. The DFT calculation indicates that electron band convergence herein improves the density of states effective mass, hence stabilizing the Seebeck coefficient. On the other hand, as the vacancies promote the point defect scattering, the lattice thermal conductivity is suppressed as well. Consequently, the synergistic effects on both electrical and thermal transport led to a peak ZT of 2.23 at 723 K and an average ZT of 1.31 across the temperature range of 303-813 K for AgMnGePb0.97SbTe5, representing improvements of 31% and 34% over the initial sample, respectively. This material creates a competitive thermoelectric performance among the Te-based thermoelectric materials, establishing a promising optimization strategy utilizing vacancy engineering.

We carried out x-ray diffraction and extended x-ray absorption fine structure studies to investigate the origin of the low lattice thermal conductivity in BiCuSeO, and the role of silver (Ag) doping in doped samples. BiCuSeO is a promising thermoelectric material with high thermoelectric efficiency, which is significantly enhanced by doping either single Ag dopants or dual dopants (Pb and Ag). We verified that the thermal displacement parameters associated with copper (Cu) are significantly large in undoped BiCuSeO. Ag dopant, which replaces Cu, was also found to have similarly large thermal displacement parameters, that remain large down to low temperatures. Our results point towards significant disorder on the Cu-site in both undoped and doped BiCuSeO, which is retained by the Ag dopant upon replacing Cu. The disorder is observed to be localized on the Cu-site and seems to be independent of other atoms in the crystal structure. Our observation of the disorder, which could be either static or quasi-static, is consistent with a 'rattling' mode scenario.

Based on first-principles calculations, the new tetragonal Janus AlSXY monolayers (X,Y = Cl, Br, I; X ≠ Y) are predicted, and the electronic structure, thermoelectric (TE) and piezoelectric properties are also explored. It is found that the system exhibits high electrical conductivity and excellent power factor due to the high carrier mobility in theY-axis direction under n-doping. Notably, the high Grüneisen parameters and low the phonon velocity lead to ultralow lattice thermal conductivity (1.35 W mK-1for AlSClBr, 1.07 W mK-1for AlSClI, and 1.06 W mK-1for AlSBrI). At 700 K, the optimal TE figure of merit reach 4.54 (AlSClBr), 8.27 (AlSClI), and 6.63 (AlSBrI) alongY-direction, surpassing previously reported 2D layered TE materials. Furthermore, the three monolayers show strong piezoelectric responses, where the piezoelectric strain coefficientd31of AlSClI reaches 0.32 pm V-1, indicating the potential applying value in high-performance TE and piezoelectric field.

A neuroevolution potential for predicting the lattice thermal conductivity of structurally disordered γ-Ga2O3

2D ferroelectric In2SSeTe with low lattice thermal conductivity and high Seebeck coefficient: A promising thermoelectric material

Low lattice thermal conductivity and high thermoelectric figure-of-merit in Ag and K2S co-doped MnTe

Ultralow lattice thermal conductivity and high thermoelectric performance in Ag2Se via defect-mediated phonon scattering

First-principles investigation of synergistic rattling and delocalization effects on ultralow lattice thermal conductivity and thermoelectric performance in Zintl phase RbSnSb

In this work, we report the enhanced thermoelectric performance of the Cd3P2 system achieved through alloying minor arsenic. The Cd3P2-based material (Cd3P1.8As0.2) achieves a peak zT exceeding 1.0 and an average zT of 0.59, comprehensively surpassing the performance of the pristine Cd3P2 compound. Such enhanced performance is attributed to the partial decoupling between electrical and thermal transport, where the reduced effective mass enhances carrier mobility, while As-induced defect scattering and increased lattice anharmonicity effectively suppress the lattice thermal conductivity. Theoretical analysis suggests further potential for improvement, thereby expanding the application prospects of this system.

ABSTRACT High‐pressure physics provides a powerful means of tuning interatomic interactions, enabling the discovery of novel structural and physical phenomena in materials. Chromium telluride, a transition metal chalcogenide, is particularly responsive to such external stimuli, exhibiting a broad spectrum of pressure‐, temperature‐, and stoichiometry‐dependent properties. One of its defining features is a pressure‐induced structural transition from a NiAs‐type to an MnP‐type phase at approximately 13 GPa, as experimentally reported by previous literature. In this work, we use density functional theory to investigate how the thermal properties — specifically, the lattice thermal conductivity — evolve across this structural transition. The complex interplay between structure and magnetism under pressure highlights the highly tunable and anisotropic nature of CrTe.

Abstract The structural, elastic, and dynamical properties of LnAuSb (Ln = La, Ce, Pr) are systematically investigated using first-principles calculations. The physical properties of LnAuSb compounds were affected by the substitution of different lanthanide elements. We observed a decrease in lattice parameters from La to Pr. This is consistent with the general trend of decreasing ionic radii throughout the lanthanide series. These changes can be attributed to lanthanide contraction behaviour. The resulting structural contraction is accompanied by a slight increase in elastic constants and phonon frequencies, indicating that the lattice is becoming stiffer and interatomic interactions are stronger. The calculated formation energies, elastic constants, and phonon dispersion curves confirm the thermodynamically, mechanical, and dynamical stability of all compounds. The estimated minimum thermal conductivity values of these compounds are low. Moreover, we observed a decrease in lattice thermal conductivity as the temperature increased. These results suggest that LnAuSb compounds (Ln = La, Ce or Pr) are promising materials for high-temperature applications, such as thermal barrier coatings and refractory systems, thanks to their directional mechanical properties and low thermal conductivity at high temperatures.

In this work, we systematically investigate the lattice thermal conductivity (κL) of LaMoN3 in the C2/c and R3c phases using first-principles calculations combined with the Boltzmann transport equation. In the C2/c phase, κL exhibits strong anisotropy, with values of 0.75 W/mK, 1.89 W/mK, and 0.82 W/mK along the a, b, and c axes, respectively, at 300 K. In contrast, the R3c phase shows nearly isotropic thermal conductivity, with values of 6.28 W/mK, 7.05 W/mK, and 7.31 W/mK along the a, b, and c directions. In both phases, acoustic and low-frequency optical phonons dominate the thermal transport. However, the C2/c phase exhibits increased three-phonon scattering leading to smaller values of κL. Additionally, four-phonon scattering plays a dominant role in the C2/c phase, reducing κL by approximately 96%, whereas in the R3c phase, it leads to a smaller but still significant reduction of ∼50%. These results highlight the critical role of four-phonon interactions in determining the thermal transport properties of LaMoN3 and reveal the stark contrast in thermal conductivity between its two structural phases.

Owing to the inherently high thermal conductivities of ternary half-Heusler (HH) thermoelectric materials, which limits substantial increase in their thermoelectric figure-of-merit (ZT), there is a pressing need to explore other systems of HH materials with intrinsic low lattice thermal conductivity. In this study, we propose the concept of equivalent valence electron principle to design quinary HH materials, the high-quality quinary Zr2CoNiSnSb and Nb2FeCoSnSb HH alloys were fabricated, that show a lower lattice thermal conductivity and higher ZT value compared with those of traditional undoped ternary materials. X-ray diffraction and aberration-corrected scanning transmission electron microscopy analyses indicated that these quinary HH alloys exhibit a typical F4̅3m space group and have good crystallinity. Band calculations further revealed that these quinary HH materials have a relatively moderate band gap and potential to be excellent thermoelectric materials. Specifically, a peak ZT value of 0.58 was obtained at 1123 K for Zr2CoNiSn0.8Sb1.2 by fine-tuning the matrix composition. The equivalent valence electron principle proposed in this paper can not only provide guidance for broadening high-performance HH systems, but also provide ideas for the design of high-entropy alloys and high-throughput screens.

Realization of unusual particle-to-wave-like crossover in phonon transport and understanding its fundamental structural origin can guide the design of materials with ultralow thermal conductivity. Here, we report such a crossover from particle-like phonon propagation to wave-like coherence with increasing temperature in the zero-dimensional (0D) metal halide, Tl2AgI3. Composed of discrete (Tl6I)5+ and (Ag3I8)5- subunits, the structure exhibits intrinsic lattice instability governed by Pauling's third rule where face-sharing of polyhedra drives Coulombic cationic repulsion causing local distortion of Ag atoms, as confirmed by synchrotron X-ray pair distribution function (X-PDF) analysis and ab initio molecular dynamics (AIMD) simulations. Anharmonic low-energy rattling of Tl is evidenced within the (Tl6I)5+ framework. These structural disorders generate low-frequency localized and anharmonic optical phonons that hybridize with acoustic branches, strongly suppressing lattice thermal conductivity ([Formula: see text]). Consequently, [Formula: see text] drops to ~0.18 W/m.K at 125 K and remains nearly temperature independent, signaling a breakdown of the phonon-gas model, attributed to phonon localization and wave-like coherence, modeled using the linearized Wigner transport equation (LWTE). The phonon localization in the 0D crystal structure results in a crossover from populations conductivity ([Formula: see text]) associated with particle-like phonon propagation to coherence conductivity ([Formula: see text]) through wave-like tunneling, at 175 K. Our study reveals 0D structural confinement along with anharmonic local structural dynamics can enable particle-to-wave-like phonon crossover, establishing a pathway to mixed phononic regimes and suppressed thermal transport.

We present a first-principles investigation of the combined effects of chemical doping and nanostructuring on the thermoelectric performance of the double halide perovskite Cs 2 NaYbCl 6 . Using density functional theory and Boltzmann transport calculations, we explicitly include all relevant scattering mechanisms (namely, electron–phonon, phonon–phonon, Coulomb impurity, phonon–impurity, and grain boundary scattering) to evaluate electrical and thermal transport coefficients. Our results show that Coulomb scattering from dopants is strongly screened and negligible compared to dominant electron–phonon interactions. Thus, both n - and p -type doping enhance electrical conductivity while only moderately reducing the Seebeck coefficient, leading to a significant increase in power factor. Phonon–impurity scattering is found to be minimal, while grain boundary scattering effectively reduces lattice thermal conductivity without strongly affecting carrier mobility. Combining optimal n -type doping ( 10 19 cm − 3 ) with nanoscale grains (10 nm), the figure of merit Z T increases from ∼ 10 − 8 in the pristine crystal to ∼ 0.12 . These findings demonstrate a viable pathway for improving thermoelectric efficiency in wide-band-gap, lead-free perovskites through controlled extrinsic modifications.

Abstract The advent of computational and experimental approaches of novel two-dimensional metal carbides
and nitrides, encompassing a variety of metal species of group IIA, IIB, IIIA and various transition metals
(collectively known as MXenes) has unveiled significant advances in materials science and technology.
Among them, alkaline-earth metal nitrides and carbides (AEXenes) have attracted enormous attention
particularly following the experimental realization of few AEXenes as a two-dimensional (2D) electride.
Herein we have systematically reviewed the structural, electronic, thermal, mechanical, magnetic and op tical properties of the 2D AEXenes, reported in recent literature. Leveraging these intriguing features, we
have assigned their prospective application across diverse domains including energy storage, energy har vesting, catalytic and spintronic devices. For instance, BeN monolayers possess significantly high storage
capacity (3489 mAh/gm) with low diffusion barrier and placing them on par with functionalized MXenes.
However, Mg2C and Mg3C2 display remarkably low lattice thermal conductivity of 20.26 W m−1K
−1 and
1.5 W m−1K
−1
, attributed to distinctive structural complexity, elevated scattering rate and ultimately facil itate better energy conversion efficiency. We have further outlined viable approaches i.e. external carrier
doping, adsorption, various defect engineering to modulate their electronic and magnetic properties to fa cilitate themselves for different applications. In this topical review, we aim to explore recent advancement
of these functionalized materials and their isoelectronic analogues to harness their exceptional properties
from both theoretical and experimental perspectives.

Abstract The two-dimensional (2D) semiconductor AlP 3 single-layer having similar structure to graphene exhibits higher thermoelectric (TE) power factor and lower lattice thermal conductivity, which is expected to be an excellent TE material. To further improve its TE performance, we obtained stable AlAsP 2 and AlAs 2 P single-layers by doping As elements in AlP 3 single-layer. By substitute arsenic atoms for phosphorus atoms, the TE conversion efficiency has been largely enhanced. Using first-principles calculation combined with the nonequilibrium Green function (NEGF) method and Landauer-Buttiker theory, we studied the electronic structures, the TE parameters and the anisotropy behavior of 2D AlAs n P 3-n (n = 0,1,2) single-layer. The calculation results showed that along the armchair direction the TE performance is superior to that along the zigzag direction, and the ZT values of AlAs n P 3-n (n = 0,1,2) single-layer by p-doping are larger than those by n-type doping. At 300 K, the armchair direction of AlAs 2 P single-layer has the highest ZT value 2.94. The doping of As atoms lead to a lower lattice thermal conductivity. This is because that the lower truncation frequency suppresses and softens the phonon mode, reducing the phonon group velocity. This study predicts potential application of AlAs n P 3-n (n = 0,1,2) single-layers in the field of TE conversion and provides a significant reference for the design of novel 2D TE devices.

NbFeSb thermoelectric materials require ultrahigh carrier concentrations (∼1021 cm-3) to optimize their electrical transport properties due to their high density-of-state effective mass, yet the heavy doping-induced atomic radius mismatch disrupts lattice potentials, degrading carrier mobility while simultaneously enhancing point defect and phonon scattering, creating a critical trade-off between electronic and phononic performance optimization. This work optimizes the thermoelectric performance of Ta-doped NbFeSb-based half-Heusler alloys via the lanthanide contraction effect. The Nb0.82-xTaxTi0.06Zr0.06Hf0.06FeSb (x = 0-0.25) alloys, synthesized through levitation melting and spark plasma sintering, exhibit exceptional room-temperature electrical conductivity (5000 S cm-1) and carrier concentrations (2 × 1021 cm-3). Ta doping enhances mass fluctuation scattering, reducing the lattice thermal conductivity by 24% while maintaining high power factors of 40 μW cm-1 K-2 across temperatures. The x = 0.1 composition achieves a peak zT of 0.8 at 973 K while maintaining excellent room-temperature electrical transport properties that are crucial for low-ΔT applications. Leveraging this material, a wearable thermoelectric wristband integrating 40 × 8 p-n modules (NbFeSb/ZrNiSn) was designed. Finite element simulations under ΔT = 16 °C demonstrate a maximum output power of 15.6 μW. Furthermore, the output power shows a positive correlation with the applied temperature gradient, highlighting its adaptability. This work highlights the synergy between lanthanide contraction-driven material optimization and device engineering, offering a robust solution for high-performance wearable thermoelectric applications.