A new thermoelectric material Ag8SnS6, with ultra-low thermal conductivity in thin film shape, is prepared on indium tin oxide coated g/ass (ITO) substrates using a chemical process via the electrodeposition techniq...A new thermoelectric material Ag8SnS6, with ultra-low thermal conductivity in thin film shape, is prepared on indium tin oxide coated g/ass (ITO) substrates using a chemical process via the electrodeposition technique. The structural, thermal and electrical properties are studied and presented in detail, which demonstrate that the material is of semiconductor type, orthorhombic structure, with a band gap in the order of 1.56eV and a free carrier concentration of 1.46 × 10^17 cm-3. The thermal conductivity, thermal diffusivity, thermal conduction mode, Seebeck coefficient and electrical conductivity are determined using the photo-thermal deflection technique combined with the Boltzmann transport theory and Cahill's model, showing that the AgsSnS6 material has a low thermal conductivity of 3.8 Wm - 1K- 1, high electrical conductivity of 2.4 × 10^5 Sm- 1, Seebeck coefficient of -180μVK-1 and a power factor of 6.9mWK-2m-1, implying that it is more efficient than those obtained in recently experimental investigations for thermoelectric devices.展开更多
The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)<sub>2</sub>) from the prospective...The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)<sub>2</sub>) from the prospective of thermoelectric applications. The calculations were performed after analytical expressions, obtained in the frame of a physical model, more detailed than the model presented earlier by authors. The main Hamiltonian of the model includes the electronic and phonon part, electron-phonon interactions and the impurity scattering term. In order to estimate the electric charge transport between the molecular chains, the physical model was upgraded to the so-called three-dimen- sional (3D) physical model. Numeric computations were performed to determine the electrical conductivity, Seebeck coefficient, thermal conductivity, thermoelectric power factor and thermoelectric figure-of-merit as a function on charge carrier concentrations, temperatures and impurity concentrations. A detailed analysis of charge-lattice interaction, consisting of the exploration of the Peierls structural transition in TCNQ molecular chains of TTT(TCNQ)<sub>2</sub> was performed. As result, the critical transition temperature was determined. The dispersion of renormalized phonons was examined in detail.展开更多
Monolayer boron-based materials are of current interests due to its polymorphism.Herein,motivated by the recent experimental synthesis of semiconducting hydrogenatedαʹ-borophene and the regulation of the physical pro...Monolayer boron-based materials are of current interests due to its polymorphism.Herein,motivated by the recent experimental synthesis of semiconducting hydrogenatedαʹ-borophene and the regulation of the physical properties in layered materials by surface functionalization,we study the thermal and electronic properties ofαʹ-borophene with three different types of gas functional groups(H,F,and Cl)based on first-principles and Boltzmann transport theory.It is found thatαʹ-borophene can be well stabilized by fluorination and chlorination and maintain the semiconductor nature.More interestingly,when hydrogen is replaced with fluorine or chlorine,the lattice thermal conductivity changes from 24.3 to 5.2 or 0.73 W/(m·K)along armchair direction at 300 K,exhibiting a huge reduction by two orders of magnitude.The main reason is the decrease of both phonon group velocities and acoustic phonon relaxation time resulting from the strong phonon mode softening due to the weaken B-B bond strength and heavier atomic mass of fluorine and chlorine.Consequently,the chlorinatedαʹ-borophene exhibits a high thermoelectric figure of merit~2 at 300 K along armchair direction.Our study illustrates the importance of the modulation of transport properties by gas functional groups,which may promote the thermoelectric application of boron-based materials.展开更多
Electrical conductivity and seebeck coefficient at different temperatures,and thermal conductivity at room temperature for various doped polyaniline (PAn) samples were measured,and the thermoelectric figure of merit Z...Electrical conductivity and seebeck coefficient at different temperatures,and thermal conductivity at room temperature for various doped polyaniline (PAn) samples were measured,and the thermoelectric figure of merit ZT was calculated.The effects of preparation methods and temperature on thermoelectric properties were discussed.The results show that the electrical conductivity and the seebeck coefficient of PAn are strongly dependent on the preparation conditions and temperature.The electrical conductivity becomes larger and the seebeck coefficient becomes smaller as PAn molecular weight increases.Redoping by organic acid and HCl results in an increase in both electrical conductivity and Seebeck coefficient of PAn,and therefore ZT value.The electrical conductivity increases and the seebeck coefficient decreases as the temperature increases when T<T d (dedoping temperature).The decreasing of the electrical conductivity and increasing of the seebeck coefficient take place by dedoping when T>T d.The thermal conductivity is lower,and insensitive to the sample preparation conditions.展开更多
The thermoelectric properties of Sr0.61Ba0.39Nb2O6-δ ceramics, reduced in different conditions, are investigated in the temperature range from 323 K to 1073 K. The electrical transport behaviors of the samples are do...The thermoelectric properties of Sr0.61Ba0.39Nb2O6-δ ceramics, reduced in different conditions, are investigated in the temperature range from 323 K to 1073 K. The electrical transport behaviors of the samples are dominated by the thermal-activated polaron hopping in the low temperature range, the Fermi glass behavior in the middle temperature range, and the Anderson localized behavior in the high temperature range. The thermal conductivity presents a plateau at high- temperatures, indicating a glass-like thermal conduction behavior. Both the thermoelectric power factor and the thermal conductivity increase with the increase of the degree of oxygen-reduction. Taking these two factors into account, the oxygen-reduction can still contribute to promoting the thermoelectric figure of merit. The highest ZT value is obtained to be -0.19 at 1073 K in the heaviest oxygen reduced sample.展开更多
The electrical properties and thermoelectric(TE) properties of monolayer In–VA are investigated theoretically by combining first-principles method with Boltzmann transport theory. The ultralow intrinsic thermal con...The electrical properties and thermoelectric(TE) properties of monolayer In–VA are investigated theoretically by combining first-principles method with Boltzmann transport theory. The ultralow intrinsic thermal conductivities of 2.64 W·m^(-1)·K^(-1)(InP), 1.31 W·m^(-1)·K^(-1)(InAs), 0.87 W·m^(-1)·K^(-1)(InSb), and 0.62 W·m^(-1) K^(-1)(InBi) evaluated at room temperature are close to typical thermal conductivity values of good TE materials(κ 〈 2 W·m^(-1)·K^(-1)). The maximal ZT values of 0.779, 0.583, 0.696, 0.727, and 0.373 for InN, InP, InAs, InSb, and InBi at p-type level are calculated at 900 K,which makes In–VA potential TE material working at medium-high temperature.展开更多
The(GeTe)_(x)(AgSbTe_(2))_(100-x)alloys,also called TAGS-x in short,have long been demonstrated as a promising candidate for thermoelectric applications with successful services as the p-type leg in radioisotope therm...The(GeTe)_(x)(AgSbTe_(2))_(100-x)alloys,also called TAGS-x in short,have long been demonstrated as a promising candidate for thermoelectric applications with successful services as the p-type leg in radioisotope thermoelectric generators for space missions.This largely stems from the complex band structure for a superior electronic performance and strong anharmonicity for a low lattice thermal conductivity.Utilization of the proven strategies including carrier concentration optimization,band and defects engineering,an extraordinary thermoelectric figure of merit,zT,has been achieved in TAGS-based alloys.Here,crystal structure,band structure,microstructure,synthesis techniques and thermoelectric transport properties of TAGS-based alloys,as well as successful strategies for manipulating the thermoelectric performance,are surveyed with opportunities for further advancements.These strategies involved are believed to be in principle applicable for advancing many other thermoelectrics.展开更多
We obtained TiNiSn-based half-Heusler Hf_(x)Ti_(1-x)NiSn_(0.97)Sb_(0.03)bulks with 85%-96%relative densities via 5-min microwave synthesis and 20-min microwave sintering in sealed vacuum.The phase composition and micr...We obtained TiNiSn-based half-Heusler Hf_(x)Ti_(1-x)NiSn_(0.97)Sb_(0.03)bulks with 85%-96%relative densities via 5-min microwave synthesis and 20-min microwave sintering in sealed vacuum.The phase composition and microstructure of samples were characterized by X-ray diffractometer(XRD)and scanning electron microscopy(SEM).Thermoelectric(TE)properties were measured,i.e.,Seebeck coefficient(S),electrical resistivity(ρ),and thermal conductivity(κ)through Seebeck coefficient/resistance analysis system(S/RAs)and laser flash thermal analyzer(LFT).The results show that the nearly single phase exists after microwave sintering.The grain sizes and the number of grain boundaries decrease with increase in Hf-doping amount due to an increase in point defects.The matrix grains for Hf_(0.1)Ti_(0.9)NiSn_(0.97)Sb_(0.03)are~10μm.The nanoscle pores and precipitates are present as second phases in matrix grain.The real composition for Hf_(0.1)Ti_(0.9)NiSn_(0.97)Sb_(0.03)matrix grain is Hf_(3.51)Ti_(28.76)-Ni_(34.76)Sn_(31.55)Sb_(1.43).The variation trends of electrical resistivity,Seebeck coefficient,power factor,and thermal conductivity were analyzed in detail.The maximum figure of merit(ZT)of 0.46 is obtained for Hf_(0.1)Ti_(0.9-)NiSnSn_(0.97)Sb_(0.03)at 723 K.The innovation route exhibits advantages for predation of TE bulks when compared to the conventional methods,especially in terms of efficiency while it still maintains TE performance.展开更多
Thermoelectric materials can be used to convert heat to electric power through the Seebeck effect. We study magneto-thermoelectric figure of merit (ZT) in three-dimensional Dirac semimetal Cd3A 5 2 crystal. It is fo...Thermoelectric materials can be used to convert heat to electric power through the Seebeck effect. We study magneto-thermoelectric figure of merit (ZT) in three-dimensional Dirac semimetal Cd3A 5 2 crystal. It is found that enhancement of power factor and reduction of thermal conductivity can be realized at the same time through magnetic field although magnetoresistivity is greatly increased. ZT can be highly enhanced from 0.17 to 1.1 by more than six times around 350 K under a perpendicular magnetic field of 7 T. The huge enhancement of ZT by magnetic field arises from the linear Dirac band with large Fermi velocity and the large electric thermal conductivity in CdsA 5 2. Our work paves a new way to greatly enhance the thermoelectric performance in the quantum topological materials.展开更多
基金Supported by the Scientific Research Deanship of University of Dammam under Grant No 2014264
文摘A new thermoelectric material Ag8SnS6, with ultra-low thermal conductivity in thin film shape, is prepared on indium tin oxide coated g/ass (ITO) substrates using a chemical process via the electrodeposition technique. The structural, thermal and electrical properties are studied and presented in detail, which demonstrate that the material is of semiconductor type, orthorhombic structure, with a band gap in the order of 1.56eV and a free carrier concentration of 1.46 × 10^17 cm-3. The thermal conductivity, thermal diffusivity, thermal conduction mode, Seebeck coefficient and electrical conductivity are determined using the photo-thermal deflection technique combined with the Boltzmann transport theory and Cahill's model, showing that the AgsSnS6 material has a low thermal conductivity of 3.8 Wm - 1K- 1, high electrical conductivity of 2.4 × 10^5 Sm- 1, Seebeck coefficient of -180μVK-1 and a power factor of 6.9mWK-2m-1, implying that it is more efficient than those obtained in recently experimental investigations for thermoelectric devices.
文摘The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)<sub>2</sub>) from the prospective of thermoelectric applications. The calculations were performed after analytical expressions, obtained in the frame of a physical model, more detailed than the model presented earlier by authors. The main Hamiltonian of the model includes the electronic and phonon part, electron-phonon interactions and the impurity scattering term. In order to estimate the electric charge transport between the molecular chains, the physical model was upgraded to the so-called three-dimen- sional (3D) physical model. Numeric computations were performed to determine the electrical conductivity, Seebeck coefficient, thermal conductivity, thermoelectric power factor and thermoelectric figure-of-merit as a function on charge carrier concentrations, temperatures and impurity concentrations. A detailed analysis of charge-lattice interaction, consisting of the exploration of the Peierls structural transition in TCNQ molecular chains of TTT(TCNQ)<sub>2</sub> was performed. As result, the critical transition temperature was determined. The dispersion of renormalized phonons was examined in detail.
基金This project is supported in part by the grants from the National Natural Science Foundation of China(Nos.12075168 and 11890703)the Science and Technology Commission of Shanghai Municipality(No.19ZR1478600).
文摘Monolayer boron-based materials are of current interests due to its polymorphism.Herein,motivated by the recent experimental synthesis of semiconducting hydrogenatedαʹ-borophene and the regulation of the physical properties in layered materials by surface functionalization,we study the thermal and electronic properties ofαʹ-borophene with three different types of gas functional groups(H,F,and Cl)based on first-principles and Boltzmann transport theory.It is found thatαʹ-borophene can be well stabilized by fluorination and chlorination and maintain the semiconductor nature.More interestingly,when hydrogen is replaced with fluorine or chlorine,the lattice thermal conductivity changes from 24.3 to 5.2 or 0.73 W/(m·K)along armchair direction at 300 K,exhibiting a huge reduction by two orders of magnitude.The main reason is the decrease of both phonon group velocities and acoustic phonon relaxation time resulting from the strong phonon mode softening due to the weaken B-B bond strength and heavier atomic mass of fluorine and chlorine.Consequently,the chlorinatedαʹ-borophene exhibits a high thermoelectric figure of merit~2 at 300 K along armchair direction.Our study illustrates the importance of the modulation of transport properties by gas functional groups,which may promote the thermoelectric application of boron-based materials.
文摘Electrical conductivity and seebeck coefficient at different temperatures,and thermal conductivity at room temperature for various doped polyaniline (PAn) samples were measured,and the thermoelectric figure of merit ZT was calculated.The effects of preparation methods and temperature on thermoelectric properties were discussed.The results show that the electrical conductivity and the seebeck coefficient of PAn are strongly dependent on the preparation conditions and temperature.The electrical conductivity becomes larger and the seebeck coefficient becomes smaller as PAn molecular weight increases.Redoping by organic acid and HCl results in an increase in both electrical conductivity and Seebeck coefficient of PAn,and therefore ZT value.The electrical conductivity increases and the seebeck coefficient decreases as the temperature increases when T<T d (dedoping temperature).The decreasing of the electrical conductivity and increasing of the seebeck coefficient take place by dedoping when T>T d.The thermal conductivity is lower,and insensitive to the sample preparation conditions.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB632506)the National Natural Science Foundation of China(Grant Nos.51202132 and 51002087)
文摘The thermoelectric properties of Sr0.61Ba0.39Nb2O6-δ ceramics, reduced in different conditions, are investigated in the temperature range from 323 K to 1073 K. The electrical transport behaviors of the samples are dominated by the thermal-activated polaron hopping in the low temperature range, the Fermi glass behavior in the middle temperature range, and the Anderson localized behavior in the high temperature range. The thermal conductivity presents a plateau at high- temperatures, indicating a glass-like thermal conduction behavior. Both the thermoelectric power factor and the thermal conductivity increase with the increase of the degree of oxygen-reduction. Taking these two factors into account, the oxygen-reduction can still contribute to promoting the thermoelectric figure of merit. The highest ZT value is obtained to be -0.19 at 1073 K in the heaviest oxygen reduced sample.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61675032 and 11604019)the National Basic Research Program of China(Grant No.2014CB643900)
文摘The electrical properties and thermoelectric(TE) properties of monolayer In–VA are investigated theoretically by combining first-principles method with Boltzmann transport theory. The ultralow intrinsic thermal conductivities of 2.64 W·m^(-1)·K^(-1)(InP), 1.31 W·m^(-1)·K^(-1)(InAs), 0.87 W·m^(-1)·K^(-1)(InSb), and 0.62 W·m^(-1) K^(-1)(InBi) evaluated at room temperature are close to typical thermal conductivity values of good TE materials(κ 〈 2 W·m^(-1)·K^(-1)). The maximal ZT values of 0.779, 0.583, 0.696, 0.727, and 0.373 for InN, InP, InAs, InSb, and InBi at p-type level are calculated at 900 K,which makes In–VA potential TE material working at medium-high temperature.
基金supported by the National Natural Science Foundation of China(Grant Nos.T2125008,92163203,and 52022068)the Innovation Program of Shanghai Municipal Education Commission,the Hefei National Laboratory for Physical Sciences at the Microscale(Grant No.KF2020007)+2 种基金the Shanghai Natural Science Foundation(Grant No.19ZR1459900)Taiyuan University of Science and Technology Scientific Research Initial Funding(No.20222002)the project supported by State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology,No.2022-KF-32)。
文摘The(GeTe)_(x)(AgSbTe_(2))_(100-x)alloys,also called TAGS-x in short,have long been demonstrated as a promising candidate for thermoelectric applications with successful services as the p-type leg in radioisotope thermoelectric generators for space missions.This largely stems from the complex band structure for a superior electronic performance and strong anharmonicity for a low lattice thermal conductivity.Utilization of the proven strategies including carrier concentration optimization,band and defects engineering,an extraordinary thermoelectric figure of merit,zT,has been achieved in TAGS-based alloys.Here,crystal structure,band structure,microstructure,synthesis techniques and thermoelectric transport properties of TAGS-based alloys,as well as successful strategies for manipulating the thermoelectric performance,are surveyed with opportunities for further advancements.These strategies involved are believed to be in principle applicable for advancing many other thermoelectrics.
基金financially supported by the National Natural Science Foundation of China (Nos.51574134 and 51574042)the Joint Fund between Shenyang National Laboratory for Materials Science and State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals (No.18LHPY016)Anhui University Outstanding Young Talent Support Program (Key Project) (No.gxyq ZD2017039)。
文摘We obtained TiNiSn-based half-Heusler Hf_(x)Ti_(1-x)NiSn_(0.97)Sb_(0.03)bulks with 85%-96%relative densities via 5-min microwave synthesis and 20-min microwave sintering in sealed vacuum.The phase composition and microstructure of samples were characterized by X-ray diffractometer(XRD)and scanning electron microscopy(SEM).Thermoelectric(TE)properties were measured,i.e.,Seebeck coefficient(S),electrical resistivity(ρ),and thermal conductivity(κ)through Seebeck coefficient/resistance analysis system(S/RAs)and laser flash thermal analyzer(LFT).The results show that the nearly single phase exists after microwave sintering.The grain sizes and the number of grain boundaries decrease with increase in Hf-doping amount due to an increase in point defects.The matrix grains for Hf_(0.1)Ti_(0.9)NiSn_(0.97)Sb_(0.03)are~10μm.The nanoscle pores and precipitates are present as second phases in matrix grain.The real composition for Hf_(0.1)Ti_(0.9)NiSn_(0.97)Sb_(0.03)matrix grain is Hf_(3.51)Ti_(28.76)-Ni_(34.76)Sn_(31.55)Sb_(1.43).The variation trends of electrical resistivity,Seebeck coefficient,power factor,and thermal conductivity were analyzed in detail.The maximum figure of merit(ZT)of 0.46 is obtained for Hf_(0.1)Ti_(0.9-)NiSnSn_(0.97)Sb_(0.03)at 723 K.The innovation route exhibits advantages for predation of TE bulks when compared to the conventional methods,especially in terms of efficiency while it still maintains TE performance.
基金supported by the National Key R&D Program of the Ministry of Science and Technology China(2017YFA0303001,2016YFA0300201 and 2017YFA0204904)the National Natural Science Foundation of China(11534010,11774325 and21603210)+4 种基金the Key Research Program of Frontier Sciences CAS(QYZDY-SSW-SLH021)Hefei Science Center CAS(2016HSCIU001)the Fundamental Research Funds for the Central UniversitiesSupercomputing Center at USTC for providing the computing resourcespartially performed on the Superconducting Magnet and PPMS-16T Facilities,High Magnetic Field Laboratory of CAS
文摘Thermoelectric materials can be used to convert heat to electric power through the Seebeck effect. We study magneto-thermoelectric figure of merit (ZT) in three-dimensional Dirac semimetal Cd3A 5 2 crystal. It is found that enhancement of power factor and reduction of thermal conductivity can be realized at the same time through magnetic field although magnetoresistivity is greatly increased. ZT can be highly enhanced from 0.17 to 1.1 by more than six times around 350 K under a perpendicular magnetic field of 7 T. The huge enhancement of ZT by magnetic field arises from the linear Dirac band with large Fermi velocity and the large electric thermal conductivity in CdsA 5 2. Our work paves a new way to greatly enhance the thermoelectric performance in the quantum topological materials.