Lattice Thermal Conductivity Research Articles

Janus-like Structure and Resonance Level Actualized Ultralow Lattice Thermal Conductivity and Enhanced ZTave in Mg3(Sb, Bi)2-Based Zintls.

Grain boundary (GB) engineering includes grain size and GB segregation. Grain size has been proven to affect the electrical properties of Mg3(Sb, Bi)2 at low temperatures. However, the formation mechanism of GB segregation and what kind of GB segregation is beneficial to the performance are still unclear. Here, the Ga/Bi cosegregation at GBs and Mg segregation within grains optimize the transport of electrons and phonons simultaneously. Ga/Bi cosegregation promotes the formation of Janus-like structures due to the diverse ordering tendencies of liquid Mg3Sb2 and Mg3Bi2 and the absence of a solid solution of Ga/Bi. The Janus-like structure significantly reduces the room-temperature lattice thermal conductivity by introducing diverse microdefects. Meanwhile, a coherent interface between the nano Mg segregation region and the matrix is formed, which reduces the thermal conductivity without affecting the carrier transport. Furthermore, the band structure calculations show that Ga doping introduces the resonance level, increasing the Seebeck coefficient. Finally, the lattice thermal conductivity reaches ∼0.4 W m-1 K-1, and a high average ZT of 1.21 between 323 and ∼773 K is achieved for Mg3.2Y0.02Ga0.03Sb1.5Bi0.5. This work provides guidance for improving the thermoelectric performance via designing cosegregation.

Enhanced thermoelectric performance of AgCuTe-doped polycrystalline SnSe by lattice plainification

Abstract Polycrystalline SnSe, renowned for its environmental sustainability, holds promise as a significant thermoelectric material, attracting considerable research attention. This study focuses on the thermoelectric properties of p-type polycrystalline SnSe doped with silver copper telluride (AgCuTe). Our experimental results conclusively show that the decomposition products of AgCuTe not only fill Sn vacancies but also act as acceptors, thereby introducing additional hole carriers. This leads to a notable improvement in both carrier mobility and concentration. Importantly, the thermal conductivity of the doped samples remains largely unchanged, as the lattice flattening strategy significantly boosts electrical performance without affecting lattice thermal conductivity. Ultimately, the doped sample Sn0.97Se-0.5%AgCuTe resulted in a power factor of 6.2 mW/mK and a peak ZT value of 1.4 at 798 K, representing a 109% improvement in ZT value. All samples exhibits superior stability and reproducibility, emphasizing its reliability for practical applications.

Unveiling the impact of four-phonon scattering on thermal transport properties of the bulk β-Ga2O3 and monolayer Ga2O3

In recent years, the role of four-phonon (4ph) scattering in thermal transport properties has been gradually revealed. However, the underlying scattering mechanisms of the bulk β-Ga2O3 and monolayer Ga2O3 remain unclear. Hence, we evaluate the effect of 4ph scattering on the thermal transport properties of the bulk β-Ga2O3 and monolayer Ga2O3 by utilizing first-principles calculations. It has been observed that the Young's modulus and lattice thermal conductivity (κ) of the bulk β-Ga2O3 are anisotropic, while the values of the monolayer Ga2O3 are isotropic. The κ of the bulk β-Ga2O3 along the three directions ([100], [010], and [001]) and monolayer Ga2O3 after adding 4ph scattering are decreased by 9.23%, 11.52%, 13.89%, and 29.24% at 300 K, respectively. Moreover, the effect of four-phonon scattering is more pronounced at the high temperature. Afterwards, based on the phonon behaviors, we can prove that the addition of 4ph scattering can increase the phonon scattering rate, decrease the phonon mean free path, and increase the phase space, which results in lower thermal conductivity. The findings can contribute to a better understanding of high-order phonon scattering mechanisms of the Ga2O3 materials.

Excellent thermoelectric performance in alkali metal phosphides M3P (M = Na and K) with phonon-glass electron-crystal like behaviour.

Identifying ideal thermoelectric materials presents a formidable challenge due to the intricate coupling relationship between thermal conductivity and power factor. Here, based on first-principles calculations, along with self-consistent phonon theory and the Boltzmann transport equation, we theoretically investigate the thermoelectric properties of alkali metal phosphides M3P (M = Na and K). The evident 'avoided crossing' phenomenon indicates the phonon glass behavior of M3P (M = Na and K). Due to the strong lattice anharmonicity induced by alkali metal elements, accounting for quartic anharmonic corrections, the lattice thermal conductivities of Na3P and K3P at room temperature are merely 0.25 and 0.12 W m-1 K-1, respectively. Furthermore, the high degeneracy and 'pudding-mold-type' band structure lead to high p-type PF in M3P (M = Na and K). At 300 K, the p-type power factors (PF) of Na3P and K3P can reach 3.90 and 0.80 mW mK-2, respectively. The combination of ultralow κL and high PF leads to excellent thermoelectric figure of merit (ZT) values of 1.70 (3.38) and 1.18 (2.13) for p-type Na3P and K3P under optimal doping concentration at 300 K (500 K), respectively, surpassing traditional thermoelectric materials. These findings demonstrate that M3P (M = Na and K) exhibits behavior similar to phonon-glass electron crystals, thereby indicating a direction for the search for high-performance thermoelectric materials.

Predicting the stability and exploring the fundamental physical properties of tetragonal Gd2O3: A comprehensive first-principles investigation

A burnable absorber is a material used in nuclear reactors to manage reactivity and extend operational cycles by absorbing neutrons. Gadolinium oxide (Gd2O3) is a prevalent burnable absorber employed in nuclear reactors. By utilizing density functional theory (DFT) within a first-principles framework, a comprehensive exploration into the physical characteristics of the predicted tetragonal phase of Gd2O3 has been effectively conducted. The investigation encompasses structural, electronic, magnetic, elastic, mechanical, bonding, thermophysical, and optical aspects. Since tetragonal Gd2O3 has not been experimentally synthesized, the stability of the tetragonal phase is confirmed through assessments of its structural, lattice dynamical, thermodynamic, and mechanical attributes. Demonstrating semiconducting behavior, the electronic nature reveals a band gap of 1.241 eV. The density of states (DOS) illustration validates the semiconductor electronic character, and the calculated magnetic moment, determined through up-down spin DOS, is 3.06 μB/f.u. The Poisson’s ratio value reflects the dominance of ionic bonding in Gd2O3, a finding corroborated by bond population analysis. Impressively, the tetragonal Gd2O3 displays elevated lattice thermal conductivity value in comparison to its cubic, monoclinic, and hexagonal counterparts. Furthermore, the determined melting point registers at 1709.31 K. In the realm of optics, an analysis based on frequency dependence reveals that tetragonal Gd2O3 holds promise as a candidate for optoelectronic applications, particularly in the ultraviolet (UV) energy range.

The role of grain boundary and alloy scattering within the Callaway model to calculate lattice thermal conductivity in GaN/AlN superlattice

The grain boundary and alloy scattering within the Debye-Callaway model were introduced to calculate the temperature-dependent lattice thermal conductivity (LTC) in the GaN/AlN superlattice. The superlattice layers are assumed to be grains, and the sample is then treated as a multigrain material. The computations include various physical parameters related to Aluminum alloy compositions, such as Debye temperature, atomic mass, lattice volume, density, alloy scattering factor and deformation energy. In general, the sample size effect on LTC in this superlattice structure was similar to any single component solids, but it has a significant influence from the grain boundaries represented by the thickness of layers in the form of LTCPeakpoint.=5.9925e0.0005L2 at the peak point maximum and LTC(600K)=0.344L at 600K, L is the sample size. The dislocations in these samples are controlled by the inbuilt AlN layers with the dependence of NDisl.=−0.542LAlN+7.4.

Synergistic strategy via modulated energy filtering and hierarchical defects evolution for high performance GeTe thermoelectrics

GeTe thermoelectric materials are very promising for sustainable waste-heat harvesting, while optimizations have been focusing on lowering lattice thermal conductivity or decreasing carrier concentration. As a long-pursued strategy to improve electronic transport properties, the full realization of effective energy filtering has been hindered by the mismatch between the energy barriers introduced and the intrinsic Fermi level of the matrix material. In this work, a synergistic strategy combining modulated energy filtering effect and hierarchical defect evolution engineering leads to ultrahigh performance GeTe-based thermoelectric materials. Very effective energy filtering is achieved by incorporating carbon fibers, which increases the overall energy of charge carriers. This greatly enhances Seebeck coefficient to over 230 μVK-1 with minor reduction in electrical conductivity which simultaneously decreases electronic thermal conductivity. Furthermore, the inclusion of carbon fibers modulates the microstructure of GeTe and facilitates the evolution of point defects to higher dimensional defects for broadband phonon scattering, greatly suppressing the lattice thermal conductivity to 0.3 Wm-1K-1. This strategy yields a prominent thermoelectric figure of merit ZTmax ∼ 2.3 and an exceptional quality factor Bmax ∼ 2.24 for Ge0.97Bi0.07Te with 0.9 wt% carbon fibers. This study demonstrates a promising strategy to modulate the convoluted thermoelectric properties for ultrahigh performance thermoelectric materials.

Cu[formula omitted]Se/MXene (Ti[formula omitted]C[formula omitted]T[formula omitted]) composite achieved ultra-low thermal conductivity and enhanced thermoelectric performance

Due to the significant mismatch in phonon density of states between carbon (C) and Cu2Se, the thermal conductivity of Cu2Se can be notably enhanced by incorporating low-dimensional carbon-based materials. This study propose an innovative approach where two-dimensional MXene material Ti3C2Tx is introduced into Cu2Se, creating numerous Cu2Se/MXene heterogeneous interfaces within the matrix. These interfaces induce high-density dislocations, which enhance multi-scale phonon scattering efficiency. Consequently, they significantly reduce lattice thermal conductivity across the entire temperature range tested. Additionally, the heterogeneous interfaces facilitate energy filtration, selectively filtering out low-energy carriers and thereby optimizing the high intrinsic carrier concentration of Cu2Se to a certain extent. Finally, the total thermal conductivity of the Cu2Se/0.4 wt% Ti3C2Tx sample at 795 K is markedly lower at 0.27 Wm−1K−1 compared to the average level of Cu2Se materials. As a result, the ZTmax reaches 2.11, reflecting a 109% enhancement compared to pristine Cu2Se.

Non‐Monotonic Variation of the Low Lattice Thermal Conductivity with Temperature in Penta‐HgO2 Sheet

AbstractInspired by the experimental synthesis of bulk HgO2 with the potential of exfoliation to form a penta‐HgO2 sheet composed entirely of pentagonal motifs, a detailed theoretical study on the lattice thermal conductivity by using first‐principles calculations combined with the unified theory of thermal transport is performed. It is found that the penta‐HgO2 sheet is semiconducting with an indirect bandgap of 1.18 eV and possesses a low lattice thermal conductivity of 2.07 W m−1 K−1 (3.28 W m−1 K−1) along the x (y)‐direction at 300 K. More interestingly, the variation of its thermal conductivity with temperature is non‐monotonic, different from most cases. The phonon dispersion, phonon scattering, and phonon coherence is further systematically investigated to understand the underlying physics. This results suggest that the strong intrinsic anharmonicity resulting from its unique atomic configuration with the buckled structure and the heavy element of Hg leads to a high scattering rate, resulting in the ultralow particle‐like thermal transport of 0.20 W m−1 K−1 (0.01 W m−1 K−1) in the x (y)‐direction, while the narrow average frequency interval and strong phonon linewidth are responsible for the dominant coherent thermal transport and non‐monotonic variation of the low lattice thermal conductivity of the penta‐HgO2 sheet.

Comparison of ultra-low lattice thermal conductivity of the full-Heusler compound Li2Rb(Cs)Bi after considering strong quartic anharmonicity

This paper conducts a detailed study on the thermal transport and thermoelectric properties of Li2Rb(Cs)Bi and analyzes the optical phonon frequency shift caused by considering anharmonicity. We mainly focus on studying the microscopic mechanism of the difference in lattice thermal conductivity (κL) of the two materials. By calculating the group velocity, scattering rate, scattering phase space and scattering sub-process, it is concluded that κL is mainly dominated by the acoustic branch. Due to its small group velocity and large scattering rate, Li2CsBi has a low κL, which is 0.60 W m−1K−1 at 300 K. Research results show that n-type Li2CsBi has a higher ZT value of about 2.1 at T = 900 K, while p-type Li2RbBi has a higher ZT value of about 1.5 at the same temperature. These results provide an important theoretical basis for the application of Li2Rb(Cs)Bi in the field of thermoelectric conversion.

Tuning of optical, thermodynamic, and thermoelectric properties of Cs2CuBiX6 (X = Cl, Br, I) halide perovskites for solar cells and energy harvesting applications

The double perovskites are outstanding materials for solar cells and transport applications to clean harvest energy. Therefore, the Cs2CuBiX6 (X = Cl, Br, I) are discussed comprehensively for energy harvesting by modified Becke and Johnson (mBJ) potential. The studied DPs fit the structural, mechanical, and dynamic stability scale by tolerance factor, Born–Huang criteria, and phonon dispersion band structures. The band gaps (1.20, 1.0, 0.70) eV for (Cl, Br, I) based DPs ensure the Cs2CuBiCl6 has an absorption band in the visible region while Cs2CuBiBr6 and Cs2CuBiI6 has an absorption band in the infrared region. Heavy elements’ spin–orbit coupling effect (Cs, Bi) reduces the band gap to 0.08 eV. Thermoelectric behavior regarding the merit scale against dopant carriers and temperature has been elaborated. The ultralow lattice thermal conductivity, large Debye temperature, hardness, and melting temperature increase their implication for thermoelectric and other thermodynamic applications. The variation in band gap makes them important for diverse optoelectric and thermoelectric applications. The Cs2CuBiCl6 with a band gap of 1.20 eV is suitable for solar cells, while Cs2CuBiBr6 and Cs2CuBiI6 with band gaps of 1.0 eV and 0.70 eV are significant for thermoelectric generators.

An interpretable formula for lattice thermal conductivity of crystals

Lattice thermal conductivity (κL) is a crucial physical property of crystals with applications in thermal management, such as heat dissipation, insulation, and thermoelectric energy conversion. However, accurately and rapidly determining κL poses a considerable challenge. In this study, we introduce a formula that achieves high precision (mean relative error = 8.97 %) and provides fast predictions, taking less than 1 min, for κL across a wide range of inorganic binary and ternary materials. Our interpretable, dimensionally aligned and physical grounded formula forecasts κL values for 4601 binary and 6995 ternary materials in the Materials Project database. Notably, we predict undiscovered high κL values for AlBN2 (κL = 101 W m−1 K−1) and the undetected low κL Cs2Se (κL = 0.98 W m−1 K−1) at room temperature. This method for determining κL streamlines the traditionally time-consuming process associated with complex phonon physics. It provides insights into microscopic heat transport and facilitates the design and screening of materials with targeted and extreme κL values through the application of phonon engineering. Our findings offer opportunities for controlling and optimizing macroscopic transport properties of materials by engineering their bulk modulus, shear modulus, and Grüneisen parameter.

Microstructural Instability and Its Effects on Thermoelectric Properties of SnSe and Na-Doped SnSe.

Effects of thermal cycling on the microstructure and thermoelectric properties are studied for the undoped and Na-doped SnSe samples using X-ray computed tomography and property measurements. It is observed that thermal cycling causes significant cracks to develop, which decrease both the electrical and lattice thermal conductivities but do not affect the thermopower. The zT values are drastically reduced after the repeated heat treatment. It is important to account for density changes during cycling to obtain accurate values of the thermal conductivity. Even before thermal cycling, the spark-plasma sintered (SPS) samples have a significant number of microcracks. The orientation of cracks within the SPS pellets and their effect on the microstructure are influenced by the presence of a Na-rich impurity. The SnSe and Sn0.995Na0.005Se samples without the impurity develop cracks and exhibit grain growth parallel to the pellet surface, which is also the plane of the 2D SnSe layers. The Sn0.97Na0.03Se sample containing the impurity develops cracks that are orthogonal to the pellet surface. Such an orientation of cracks in Sn0.97Na0.03Se inhibits grain growth. All samples appear mechanically unstable after thermal cycling.

Challenges Reconciling Theory and Experiments in the Prediction of Lattice Thermal Conductivity: The Case of Cu-Based Sulvanites.

The exploration of large chemical spaces in search of new thermoelectric materials requires the integration of experiments, theory, simulations, and data science. The development of high-throughput strategies that combine DFT calculations with machine learning has emerged as a powerful approach to discovering new materials. However, experimental validation is crucial to confirm the accuracy of these workflows. This validation becomes especially important in understanding the transport properties that govern the thermoelectric performance of materials since they are highly influenced by synthetic, processing, and operating conditions. In this work, we explore the thermal conductivity of Cu-based sulvanites by using a combination of theoretical and experimental methods. Previous discrepancies and significant variations in reported data for Cu3VS4 and Cu3VSe4 are explained using the Boltzmann Transport Equation for phonons and by synthesizing well-characterized defect-free samples. The use of machine learning approaches for extracting high-order force constants opens doors to charting the lattice thermal conductivity across the entire Cu-based sulvanite family-finding not only materials with κ l values below 2 W m-1 K-1 at moderate temperatures but also rationalizing their thermal transport properties based on chemical composition.

Nanostructured Ferecrystal Intergrowths with TaSe2 Unveiled High Thermoelectric Performance in n-Type SnSe.

Ferecrystals, a distinctive class of misfit layered compounds, hold significant promise in manipulating the phonon transport owing to their two-dimensional (2D) natural superlattice-type structure and turbostratic (rotational) disorder present between the constituent layers. Integrating these 2D intergrowth structures as nanodomains embedded in a bulk thermoelectric matrix is a formidable challenge in synthetic chemistry, yet offers groundbreaking opportunities for efficient thermoelectrics. Here, we have achieved an exceptionally high thermoelectric figure of merit, zT ∼ 2.2, at 823 K in n-type Ta and Br-codoped SnSe, by successfully incorporating [(SnSe)1.15]7(TaSe2)1 ferecrystals with [110] SnSe//[100] TaSe2 orientation, as nanostructures with modulations in few nm in bulk SnSe solid-state matrix. While the presence of ferecrystal nanostructures induces strong scattering of heat-carrying phonons resulting in an ultralow lattice thermal conductivity (κL) of ∼0.18 W m-1 K-1 at 773 K, the Ta and Br codoping strategy increases the concentration of n-type charge carriers for enhanced electrical conductivity. Our approach provides a new pathway for damping the phonon transport and enhancing the thermoelectric performance in 2D layered materials.

Carrier-phonon decoupling in perovskite thermoelectrics via entropy engineering

Thermoelectrics converting heat and electricity directly attract broad attentions. To enhance the thermoelectric figure of merit, zT, one of the key points is to decouple the carrier-phonon transport. Here, we propose an entropy engineering strategy to realize the carrier-phonon decoupling in the typical SrTiO3-based perovskite thermoelectrics. By high-entropy design, the lattice thermal conductivity could be reduced nearly to the amorphous limit, 1.25 W m−1 K−1. Simultaneously, entropy engineering can tune the Ti displacement, improving the weighted mobility to 65 cm2 V−1 s−1. Such carrier-phonon decoupling behaviors enable the greatly enhanced μW/κL of ~5.2 × 103 cm3 K J−1 V−1. The measured maximum zT of 0.24 at 488 K and the estimated zT of ~0.8 at 1173 K in (Sr0.2Ba0.2Ca0.2Pb0.2La0.2)TiO3 film are among the best of n-type thermoelectric oxides. These results reveal that the entropy engineering may be a promising strategy to decouple the carrier-phonon transport and achieve higher zT in thermoelectrics.

Study of the physical properties of the half-heusler XBrH with (X= sr, Ca and mg) compounds

Half-Heusler alloys are among the most promising thermoelectric materials for medium- and high-temperature waste heat recovery applications. This study investigates the physical properties of Half-Heusler compounds XBrH, with X = Sr, Ca, and Mg. We explored the structural, electronic, optical, and thermoelectric properties of these compounds using density functional theory (DFT) as implemented in the Wien2k package. The Generalized Gradient Approximation (GGA) as proposed by Perdew-Burke-Ernzerhof (PBE) and the modified Becke-Johnson (mBJ) functional were employed to calculate the exchange-correlation interactions. After doing structural optimization for a range of parameters, we discovered that the SrBrH compound is more stable than the CaBrH and MgBrH compounds. Our results show that the density of state calculations indicate semiconductor behavior for the XBrH with (X = Sr, Ca, and Mg) compounds. We also evaluated the real and imaginary parts of the dielectric tensor, the refractive index, the absorption coefficient, the electron energy loss, and the real and imaginary components of the optical conductivity, among other optical parameters. Additionally, we investigated the figure of merit (ZT), electronic and lattice thermal conductivity, Seebeck coefficient, and electrical conductivity. The MgBrH, CaBrH and SrBrH compounds showed p-type behavior, with positive values for the Seebeck coefficient and the greatest value of ≈180 μV/K, according to the thermoelectric data. At 1000 K, the ZT reach their highest values for CaBrH, SrBrH, and MgBrH, respectively, at 2.9, 2.8, and 0.9. The physical properties of the XBrH with (X = Sr, Ca, and Mg) compounds have been studied in detail.

Electronic structure and phonon transport properties of HfSe2 under in-plane strain and finite temperature

The electronic structure and phonon transport properties of HfSe2 under different in-plane strains at finite temperatures are systematically investigated by combining first-principles calculations with machine learning force field molecular dynamics simulations. Within a strain range of -3% to 3%, the electronic band gap value of HfSe2 varies between 0.39 and 0.87 eV. Under compressive strain, the conduction band minimum moves towards the Fermi level, with the distribution of electrons near the valence band maximum becoming more delocalized. This will reduce the scattering of electrons during the transport process, helping to improve the carrier mobility. Under tensile strain, the localization of the density of states near the valence band maximum is strengthened, accompanied by enhanced metallic properties of the Hf-Se bonds, which facilitates the enhancement of the thermoelectric power factor. Both compressive and tensile strains intensify the coupling of phonon normal modes with phonon scattering, and elevating the temperature amplifies this impact. The anharmonicity-induced reduction in phonon frequencies is especially pronounced for modes in the vicinity of the Debye frequency. This not only curtails the phonon lifetimes but also diminishes the lattice thermal conductivity through the enhancement of vibrational coupling among optical branches and the reduction of the group velocity in acoustic branches. These results demonstrate the synergistic effects of strain and temperature on the electronic structure and phonon transport of HfSe2.

Thermoelectric Performance of Non-Stoichiometric Permingeatite Cu3+mSbSe4.

Non-stoichiometric permingeatites Cu3+mSbSe4 (-0.04 ≤ m ≤ -0.02) were synthesized, and their thermoelectric properties were examined depending on the Cu deficiency. Phase analysis by X-ray diffraction revealed no detection of secondary phases. Due to Cu deficiency, the lattice parameters of tetragonal permingeatite decreased compared to the stoichiometric permingeatite, resulting in a = 0.5654-0.5654 nm and c = 1.1253-1.1254 nm, with a decrease in the c/a ratio in the range of 1.9901-1.9903. Electrical conductivity exhibited typical semiconductor behavior of increasing conductivity with temperature, and above 423 K, the electrical conductivity of all samples exceeded that of stoichiometric permingeatite; Cu2.96SbSe4 exhibited a maximum of 9.8 × 103 Sm-1 at 623 K. The Seebeck coefficient decreased due to Cu deficiency, showing p-type semiconductor behavior similar to stoichiometric permingeatite, with majority carriers being holes. Thermal conductivity showed negative temperature dependence, and both electronic and lattice thermal conductivities increased due to Cu deficiency. Despite the decrease in the Seebeck coefficient due to Cu deficiency, the electrical conductivity increased, resulting in an increase in the power factor (especially a great increase at high temperatures), with Cu2.97SbSe4 exhibiting the highest value of 0.72 mWm-1K-2 at 573 K. As the carrier concentration increased due to Cu deficiency, the thermal conductivity increased, but the increase in power factor was significant, with Cu2.98SbSe4 recording a maximum dimensionless figure-of-merit of 0.50 at 523 K. This value was approximately 28% higher than that (0.39) of stoichiometric Cu3SbSe4.

Vacancy Manipulation by Ordered Mesoporous Induced Optimal Carrier Concentration and Low Lattice Thermal Conductivity in BixSb2- xTe3 Yielding Superior Thermoelectric Performance.

For BixSb2- xTe3 (BST) in thermoelectric field, the element ratio is easily influenced by the chemical environment, deviating from the stoichiometric ratio and giving rise to various intrinsic defects. In P-type polycrystalline BST, SbTe and BiTe are the primary forms of defects. Defect engineering is a crucial strategy for optimizing the electrical transport performance of Bi2Te3-based materials, but achieving synchronous improvement of thermal performance is challenging. In this study, mesoporous SiO2 is utilized to successfully mitigate the adverse impacts of vacancy defects, resulting in an enhancement of the electrical transport performance and a pronounced reduction in thermal conductivity. Crystal and the microstructure of the continuous modulation contribute to the effective phonon-electronic decoupling. Ultimately, the peak zT of Bi0.4Sb1.6Te3/0.8 wt% SiO2 (with a pore size of 4nm) nanocomposites reaches as high as 1.5 at 348 K, and a thermoelectric conversion efficiency of 6.6% is achieved at ΔT = 222.7 K. These results present exciting possibilities for the realization of defect regulation in porous materials and hold reference significance for other material systems.