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
Our community currently deals with issues such as rising electricity costs,pollution,and global warming.Scientists work to improve energy harvesting-based power generators in order to reduce their impacts.The Seebeck ...Our community currently deals with issues such as rising electricity costs,pollution,and global warming.Scientists work to improve energy harvesting-based power generators in order to reduce their impacts.The Seebeck effect has been used to illustrate the capacity of thermoelectric generators(TEGs)to directly convert thermal energy to electrical energy.They are also ecologically beneficial since they do not include chemical products,function quietly because they lack mechanical structures and/or moving components,and may be built using different fabrication technologies such as three-dimentional(3D)printing,silicon technology,and screen printing,etc.TEGs are also position-independent and have a long operational lifetime.TEGs can be integrated into bulk and flexible devices.This review gives further investigation of TEGs,beginning with a full discussion of their operating principle,kinds,materials utilized,figure of merit,and improvement approaches,which include various thermoelectric material arrangements and utilised technologies.This paper also discusses the use of TEGs in a variety of disciplines such as automobile and biomedical.展开更多
The thermoelectric effect of the system is theoretically investigated,by coupling Majorana zero mode to the T-typed double-quantum-dot-structure in different ways.It is found that when a single Majorana zero mode is c...The thermoelectric effect of the system is theoretically investigated,by coupling Majorana zero mode to the T-typed double-quantum-dot-structure in different ways.It is found that when a single Majorana zero mode is coupled to one of the quantum dots(QDs),the thermoelectric efficiency is suppressed due to the leakage of Majorana zero modes into the QDs.When the Majorana zero mode is coupled to QD2,the suppression of the thermoelectric efficiency is more serious than that of QD1.Furthermore,when two Majorana zero modes are introduced simultaneously,suppression of the thermoelectric effect still takes place.We believe that such results can be candidates for the detection of Majorana bound states and help us understand the role of Majorana zero mode in thermoelectricity.展开更多
In the present study,we have synthesized Ag2Te nanoparticles using the hydrothermal method and showed significant improvement in the thermoelectric properties compared to the bulk Ag2Te sample.Ag2Te nanoparticles show...In the present study,we have synthesized Ag2Te nanoparticles using the hydrothermal method and showed significant improvement in the thermoelectric properties compared to the bulk Ag2Te sample.Ag2Te nanoparticles showed the highest figure of merit(zT)of 1.37 at 373 K,which is the highest zT reported for this undoped material.This high zT in Ag2Te nanoparticles is mainly due to about~2 times higher electrical conductivity(1967 S/cm)and subsequently~2 times lower thermal conductivity(0.53 W/(m$K))as compared to the bulk Ag2Te sample.The higher electrical conductivity in Ag2Te nanoparticles can be accredited for two reasons(i)better mobility of the charge carrier and(ii)increased carrier concentration.The low thermal conductivity is associated with the enhanced scattering of phonons at the interface of the Ag2Te nanoparticles.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(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
Thermoelectric technologies have caught our intense attention due to their ability of heat conversion into electricity.The considerable efforts have been taken to develop and enhance thermoelectric properties of mater...Thermoelectric technologies have caught our intense attention due to their ability of heat conversion into electricity.The considerable efforts have been taken to develop and enhance thermoelectric properties of materials over the past several decades.Recently,twodimensional layered materials are making the promise for potential applications of thermoelectric devices because of the excellent physical and structural properties.Here,a comprehensive coverage about recent progresses in thermoelectric properties of typical two dimensional(2D)layered materials,including the theoretical and experimental results,is provided.Moreover,the potential applications of 2D thermoelectric materials are also involved.These results indicate that the development of 2D thermoelectric materials take a key role in the flexible electronic devices with thermoelectric technologies.展开更多
Micro crystalline materials of BiCoO3 and Ni0.5Bi0.5CoO3 have been prepared by solid state reaction technique. XRD studies of these polycrystalline materials confirmed the cubic structure with 197 I 23 space group. Th...Micro crystalline materials of BiCoO3 and Ni0.5Bi0.5CoO3 have been prepared by solid state reaction technique. XRD studies of these polycrystalline materials confirmed the cubic structure with 197 I 23 space group. The substitution of nickel in place of bismuth resulted in lattice contraction. The thermoelectric properties were investigated in the temperature ranging from 300°C to 700°C. The samples showed positive Seebeck coefficient. Nickel substitution with Bismuth is found to decrease the Seebeck coefficient and thermal conductivity but increase the electrical conductivity. The figure of merit (ZT) of the material was enhanced on nickel substitution. The ZT values increased with the increase of temperature which enables its utility in high temperature thermoelectric applications.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
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
采用合金设计、真空熔炼、快速凝固、球磨制粉、冷压成形和常压烧结工艺,制备了Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料,采用XRD、SEM和ZEM-3热电测试系统等表征热电材料晶体结构、微观形貌和热电性能,研究Cu、S掺杂的n型Bi_(2)T...采用合金设计、真空熔炼、快速凝固、球磨制粉、冷压成形和常压烧结工艺,制备了Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料,采用XRD、SEM和ZEM-3热电测试系统等表征热电材料晶体结构、微观形貌和热电性能,研究Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料热电性能机理。结果表明:Cu_(y)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)热电材料晶体结构为R-3m空间群斜方晶系的六面体层状结构;掺杂Cu的Cu_(y)Bi_(2)Te_(2.7)Se_(0.3)热电材料,形成Cui间隙缺陷和Bi′Te反位缺陷,随着载流子(电子)浓度增加,载流子迁移率降低,电导率显著增大;掺杂S的Bi_(2)Te_(2.62-z)SzSe_(0.3)热电材料,生成化学键健能较Bi-Te强的Bi-S,抑制反位缺陷Bi′Te形成,少数(空穴)载流子浓度减小,同时增强声子对声子散射和点缺陷对声子散射,从而使晶格热导率和双极扩散热导率降低,总热导率明显降低,抑制塞贝克系数的减少;Cu、S共掺杂的协同作用,n型Cu_(y)Bi_(2)Te_(2.62-z)SzSe_(0.3)热电材料电导率增大,而热导率基本不变,由此ZT值和功率因子显著提高;在300~400 K温度范围内,Cu_(0.03)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)的电导率约为7.0×10^(4)S/m,塞贝克系数约为220μV/K,功率因子约为2.4 m W/(m·K^(2)),热电优值(ZT值)约为1.0。Cu_(0.03)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)热电材料可广泛应用于低温尤其室温条件下的热电制冷器件和温差发电电池。展开更多
Tuning the charge carrier concentration is imperative to optimize the thermoelectric(TE)performance of a material.For BiCuSeO based oxyselenides,doping efforts have been limited to optimizing the carrier concentration...Tuning the charge carrier concentration is imperative to optimize the thermoelectric(TE)performance of a material.For BiCuSeO based oxyselenides,doping efforts have been limited to optimizing the carrier concentration.In the present work,dual-doping of In and Pb at Bi site is introduced for p-type BiCuSeO to realize the electric transport channels with intricate band characteristics to improve the power factor(PF).Herein,the impurity resonant state is realized via doping of resonant dopant In over Pb,where Pb comes forward to optimize the Fermi energy in the dual-doped BiCuSeO system to divulge the significance of complex electronic structure.The manifold roles of dual-doping are used to adjust the elevation of the PF due to the significant enhancement in electrical properties.Thus,the combined experimental and theoretical study shows that the In/Pb dual doping at Bi sites gently reduces bandgap,introduces resonant doping states with shifting down the Fermi level into valence band(VB)with a larger density of state,and thus causes to increase the carrier concentration and effective mass(m*),which are favorable to enhance the electronic transport significantly.As a result,both improved ZTmax=0.87(at 873 K)and high ZTave=0.5(at 300–873 K)are realized for InyBi(1−x)−yPbxCuSeO(where x=0.06 and y=0.04)system.The obtained results successfully demonstrate the effectiveness of the selective dual doping with resonant dopant inducing band manipulation and carrier engineering that can unlock new prospects to develop high TE materials.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
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.
文摘Our community currently deals with issues such as rising electricity costs,pollution,and global warming.Scientists work to improve energy harvesting-based power generators in order to reduce their impacts.The Seebeck effect has been used to illustrate the capacity of thermoelectric generators(TEGs)to directly convert thermal energy to electrical energy.They are also ecologically beneficial since they do not include chemical products,function quietly because they lack mechanical structures and/or moving components,and may be built using different fabrication technologies such as three-dimentional(3D)printing,silicon technology,and screen printing,etc.TEGs are also position-independent and have a long operational lifetime.TEGs can be integrated into bulk and flexible devices.This review gives further investigation of TEGs,beginning with a full discussion of their operating principle,kinds,materials utilized,figure of merit,and improvement approaches,which include various thermoelectric material arrangements and utilised technologies.This paper also discusses the use of TEGs in a variety of disciplines such as automobile and biomedical.
基金High-level talents research project of Yingkou Institute of Technology(Grant No.YJRC202027)the Natural Science Foundation of Liaoning Province of China(Grant No.2020-BS-287).
文摘The thermoelectric effect of the system is theoretically investigated,by coupling Majorana zero mode to the T-typed double-quantum-dot-structure in different ways.It is found that when a single Majorana zero mode is coupled to one of the quantum dots(QDs),the thermoelectric efficiency is suppressed due to the leakage of Majorana zero modes into the QDs.When the Majorana zero mode is coupled to QD2,the suppression of the thermoelectric efficiency is more serious than that of QD1.Furthermore,when two Majorana zero modes are introduced simultaneously,suppression of the thermoelectric effect still takes place.We believe that such results can be candidates for the detection of Majorana bound states and help us understand the role of Majorana zero mode in thermoelectricity.
基金The Department of Science and Technology(DST)of the Government of India(project no.RP03530)and the Ministry of Electronics and Information Technology(MeitY)have both offered financial assistance.The authors also thank Nanoscale Research Facility(NRF)for using different characterization techniques.Author A.K.Gautam is also grateful to the Council of Scientific and Industrial Research(CSIR)for the senior research fellowship(SRF)Grant.
文摘In the present study,we have synthesized Ag2Te nanoparticles using the hydrothermal method and showed significant improvement in the thermoelectric properties compared to the bulk Ag2Te sample.Ag2Te nanoparticles showed the highest figure of merit(zT)of 1.37 at 373 K,which is the highest zT reported for this undoped material.This high zT in Ag2Te nanoparticles is mainly due to about~2 times higher electrical conductivity(1967 S/cm)and subsequently~2 times lower thermal conductivity(0.53 W/(m$K))as compared to the bulk Ag2Te sample.The higher electrical conductivity in Ag2Te nanoparticles can be accredited for two reasons(i)better mobility of the charge carrier and(ii)increased carrier concentration.The low thermal conductivity is associated with the enhanced scattering of phonons at the interface of the Ag2Te nanoparticles.
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Thanks for the support of the National Key R&D Program of China under Grant No.2016YFA0200400 and the National Natural Science Foundation of China under Grant No.51627805。
文摘Thermoelectric technologies have caught our intense attention due to their ability of heat conversion into electricity.The considerable efforts have been taken to develop and enhance thermoelectric properties of materials over the past several decades.Recently,twodimensional layered materials are making the promise for potential applications of thermoelectric devices because of the excellent physical and structural properties.Here,a comprehensive coverage about recent progresses in thermoelectric properties of typical two dimensional(2D)layered materials,including the theoretical and experimental results,is provided.Moreover,the potential applications of 2D thermoelectric materials are also involved.These results indicate that the development of 2D thermoelectric materials take a key role in the flexible electronic devices with thermoelectric technologies.
文摘Micro crystalline materials of BiCoO3 and Ni0.5Bi0.5CoO3 have been prepared by solid state reaction technique. XRD studies of these polycrystalline materials confirmed the cubic structure with 197 I 23 space group. The substitution of nickel in place of bismuth resulted in lattice contraction. The thermoelectric properties were investigated in the temperature ranging from 300°C to 700°C. The samples showed positive Seebeck coefficient. Nickel substitution with Bismuth is found to decrease the Seebeck coefficient and thermal conductivity but increase the electrical conductivity. The figure of merit (ZT) of the material was enhanced on nickel substitution. The ZT values increased with the increase of temperature which enables its utility in high temperature thermoelectric applications.
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.
文摘采用合金设计、真空熔炼、快速凝固、球磨制粉、冷压成形和常压烧结工艺,制备了Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料,采用XRD、SEM和ZEM-3热电测试系统等表征热电材料晶体结构、微观形貌和热电性能,研究Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料热电性能机理。结果表明:Cu_(y)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)热电材料晶体结构为R-3m空间群斜方晶系的六面体层状结构;掺杂Cu的Cu_(y)Bi_(2)Te_(2.7)Se_(0.3)热电材料,形成Cui间隙缺陷和Bi′Te反位缺陷,随着载流子(电子)浓度增加,载流子迁移率降低,电导率显著增大;掺杂S的Bi_(2)Te_(2.62-z)SzSe_(0.3)热电材料,生成化学键健能较Bi-Te强的Bi-S,抑制反位缺陷Bi′Te形成,少数(空穴)载流子浓度减小,同时增强声子对声子散射和点缺陷对声子散射,从而使晶格热导率和双极扩散热导率降低,总热导率明显降低,抑制塞贝克系数的减少;Cu、S共掺杂的协同作用,n型Cu_(y)Bi_(2)Te_(2.62-z)SzSe_(0.3)热电材料电导率增大,而热导率基本不变,由此ZT值和功率因子显著提高;在300~400 K温度范围内,Cu_(0.03)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)的电导率约为7.0×10^(4)S/m,塞贝克系数约为220μV/K,功率因子约为2.4 m W/(m·K^(2)),热电优值(ZT值)约为1.0。Cu_(0.03)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)热电材料可广泛应用于低温尤其室温条件下的热电制冷器件和温差发电电池。
基金Present work was supported by Guangdong Basic and Applied Basic Research Foundation(Nos.2019A1515110107 and 2020A1515010515)the National Natural Science Foundation of China(No.11604212)。
文摘Tuning the charge carrier concentration is imperative to optimize the thermoelectric(TE)performance of a material.For BiCuSeO based oxyselenides,doping efforts have been limited to optimizing the carrier concentration.In the present work,dual-doping of In and Pb at Bi site is introduced for p-type BiCuSeO to realize the electric transport channels with intricate band characteristics to improve the power factor(PF).Herein,the impurity resonant state is realized via doping of resonant dopant In over Pb,where Pb comes forward to optimize the Fermi energy in the dual-doped BiCuSeO system to divulge the significance of complex electronic structure.The manifold roles of dual-doping are used to adjust the elevation of the PF due to the significant enhancement in electrical properties.Thus,the combined experimental and theoretical study shows that the In/Pb dual doping at Bi sites gently reduces bandgap,introduces resonant doping states with shifting down the Fermi level into valence band(VB)with a larger density of state,and thus causes to increase the carrier concentration and effective mass(m*),which are favorable to enhance the electronic transport significantly.As a result,both improved ZTmax=0.87(at 873 K)and high ZTave=0.5(at 300–873 K)are realized for InyBi(1−x)−yPbxCuSeO(where x=0.06 and y=0.04)system.The obtained results successfully demonstrate the effectiveness of the selective dual doping with resonant dopant inducing band manipulation and carrier engineering that can unlock new prospects to develop high TE materials.
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.