82 results about "Lattice thermal conductivity" patented technology

The invention discloses a nanophase doped bismuth telluride-based thermoelectric material and a preparation method thereof. The bismuth telluride-based thermoelectric material is characterized in taking the bismuth telluride-based thermoelectric material containing a tellurium element, a bismuth element and a doped chemical element, as a matrix. The doped nanophase is a one-dimensional nanophase,and the weight of the one-dimensional nanophase accounts for 0.01-5 percent of the weight of the matrix. Attapulgite or a zinc oxide nanowire or a single-wall carbon nanotube or a multi-wall carbon nanotube is preferable to the one-dimensional nanophase. Compared with the prior art, in the bismuth telluride-based thermoelectric material, the lattice heat conductivity within the whole temperature zone range is reduced, thereby a ZT value is greatly improved and the thermoelectric performance of the bismuth telluride-based thermoelectric material is improved. The preparation method is simple and easy to implement, and compared with other methods of balling milling or liquid phase and the like, impurities are not easy to introduce in the preparation method so that the one-dimensional nanophase is evenly staggered and distributed in the matrix and the mechanical property of the material is effectively improved.

The present invention relates to filled skuterudite-base thermoelectrical composite material and its preparation process, and belongs to the field of thermoelectrical material preparing technology. The thermoelectrical composite material has the composition of IyA4B12/zIOx, where I is one of Yb, Eu, Ce, La, Nd, Ca and Sr; A is Sb or its mixture with one of Ge, Sn, Te and Se; B is Co or its mixture with Fe or Ni; y is the amount of I element, y+z=m, and m is greater than the filling limit of filling atom. The thermoelectrical composite material is prepared through first smelting process to produce block material, the subsequent mechanical crushing and grinding to obtain powder, and the final fast sintering with pulse DC current to form compact block. The material has lowered lattice heat conductivity, maintained electric transmission performance and raised thermoelectrical conversion performance.

The invention discloses a nanoparticle composite bismuth telluride-based thermoelectric material and a preparation method thereof. In the nanoparticle composite bismuth telluride-based thermoelectric material, a bismuth telluride thermoelectric material is used as a substrate, and nanoparticles are mixed in the substrate, wherein the nanoparticles are electrical-conduction oxide nanoparticles. Compared with the prior art, since the electrical-conduction oxide nanoparticles are used as a second phase and compounded with a bismuth telluride-based alloy substrate; on one hand, the electrical-conduction oxide nanoparticles can enhance the selective scattering to low-frequency phonons so that the crystal lattice heat conductivity of the bismuth telluride-based thermoelectric material can be effectively reduced, and on the other hand, the electrical-conduction oxide nanoparticles can improve the electrical conductivity of the material on the other hand, therefore, an integral regulation and control effect improves the thermoelectric figure of merit ZR of the bismuth telluride-based thermoelectric material so that the thermoelectric property of the bismuth telluride-based thermoelectric material is optimized.

The invention relates to a high-performance thermoelectric composite material and a preparation method thereof, belonging to the field of thermoelectric materials. The composite material consists of two phases. A first phase is n-type Bi2Te3-Bi2Se3 or p-type Bi2Te3-Sb2Te3, and a second phase is nanometer powder of a metallic oxide. The nanometer powder of the metallic oxide accounts for 0.05-10% in terms of the total weight of the thermoelectric composite material. According to the preparation method provided by the invention, the n-type Bi2Te3-Bi2Se3 or p-type Bi2Te3-Sb2Te3 powder is ultrasonically mixed with the nanometer oxide, and discharge plasma sintering is carried out on the mixture to obtain a dense block material. Compared with the bismuth-telluride-based thermoelectric base material, under the condition that the electric conductivity of the thermoelectric base material is maintained to be unchanged basically in the invention, the high-performance thermoelectric composite material, provided by the invention, achieves the advantages of obviously reduced lattice heat conductivity and increased Seeback coefficient, and therefore the thermoelectric performance of the material can be greatly improved.

The invention relates to an argyrodite thermoelectric material, the chemical formula of which is Ag8Sn(1-x)NbxSe6, x=0-0.05. The preparation method of the argyrodite thermoelectric material is characterized by, with simple substances being raw materials, carrying out material blending according to stoichiometric ratio of the chemical formula; after vacuum packaging, melting reaction quenching and thermal treatment quenching, grinding ingots into powders; and carrying out vacuum high-temperature hot-pressure sintering, and after slow cooling, obtaining a block material, which is the argyrodite thermoelectric material. Compared with the prior art, the high-performance thermoelectric material, which is low in heat conduction and high in thermoelectric performance, is prepared, and the method for preparing the thermoelectric material, which is high in density, high in mechanical strength and high in thermoelectric performance, is explored; the thermoelectric material has very low lattice thermal conductivity (0.2-0.4 W/m.K) in a whole-temperature range; when the temperature is 900 K, thermoelectric peak of the thermoelectric material reaches 1.2; when the temperature is 300-850 K, the average thermoelectric figure of merit zTave of the thermoelectric material is infinity-0.8; and the argyrodite thermoelectric material is a potential thermoelectric material.

The invention provides a measuring method for thermal conductivity of metal at high temperature. The measuring method comprises the following steps: acquiring thermal diffusion coefficients of a metal sample at different temperatures, wherein the temperatures refer to temperatures except the oxidizing temperature of the metal sample; acquiring thermal conductivity at a corresponding temperature according to the thermal diffusion coefficients and the density and specific heat capacity of the metal sample; acquiring a plurality of groups of initialization fitting regression equation of the temperatures and thermal conductivity according to each group of temperature and thermal conductivity data; subjecting each group of initialization fitting regression equation to test of goodness of fit according to the temperatures and thermal conductivity and establishing a fitting regression model of the temperatures and thermal conductivity; and determining thermal conductivity at different high temperatures according to the fitting regression model. With the method provided by the invention, thermal conductivity of metal at high temperature can be obtained, and accuracy of the obtained thermal conductivity is high.

The invention relates to a high-performance silver-tellurium compound thermoelectric semiconductor material and a preparation method thereof. The chemical formula of the silver-tellurium compound thermoelectric semiconductor material is Ag5-xTe3, wherein x satisfies a relational expression that -0.04<=x<=0.14. According to the preparation of the silver-tellurium compound thermoelectric semiconductor material, high-purity simple substances are adopted as raw materials; the materials are selected according to a stoichiometric ratio in the above chemical formula; and the materials are subjected to vacuum encapsulation, high-temperature melting, annealing and heat treatment, and obtained substances are ground into powder, and the powder is subjected to vacuum hot-pressing and sintering, and slow cooling, so that a sheet-like block material is obtained, the sheet-like block material is a target product. Compared with the prior art, the thermoelectric semiconductor material of the inventionproduced by using the preparation method of the invention has the advantages of extremely low thermal conductivity and high thermoelectric performance; the lattice thermal conductivity of the thermoelectric material is as low as 0.18 to 0.25W/m.K in a full temperature range; the thermoelectric figure of merit of the thermoelectric material reaches 1.0 when temperature reaches 650K; and the thermoelectric material has a great potential. With the invention adopted, a preparation process for obtaining a high-quality polycrystalline sample is explored.

The invention relates to a Nano SiC/P-type silicon germanium alloy-based thermoelectric composite material and a preparation method thereof. The thermoelectric composite material is composed of P-type silicon germanium alloy and Nano SiC particles uniformly dispersed on the grain boundary and/or inside the grains of the P-type silicon germanium alloy. The chemical formula of the P-type silicon germanium alloy is Si(80)Ge(20)B(x), wherein 0.2<=x<=2.0. The volume percentage of the Nano SiC particles is 0.3-2.0% that of the P-type silicon germanium alloy. The Nano SiC particles and the P-type silicon germanium alloy are composited to prepare the thermoelectric composite material. The lattice thermal conductivity of the material is reduced significantly on the premise that the power factor does not change much. The thermoelectric property of the material in the whole range of temperature is improved. In addition, the preparation method provided by the invention is simple and fast, has high utilization ratio of raw materials, and has a good industrialization prospect.

The invention provides a Mg-Si-Sn-based nano-composite thermoelectric material and a preparation method thereof. The Mg-Si-Sn-based nano-composite thermoelectric material has a layered structure, and the chemical general formula of the Mg-Si-Sn-based nano-composite thermoelectric material is Mg2SixSn1-xMy, wherein M is a doping element and is one selected from Sb, Bi, Ga, Ag, Cu and Al, x is not less than 0.3 and not more than 0.9, and y is not less than 0.005 and not more than 0.15; the structures of all layers have different Mg:Si:Sn atom mole content ratios and different M doping concentrations; and the structure of each of all the layers comprises a Mg-Si-Sn matrix and a Mg-Si-Sn nanometer grain second phase dispersed in the matrix to form a coherent interface or a semi-coherent interface. The Mg-Si-Sn-based nanocomposite thermoelectric material has a coherent interface and a modulation-doped structure, so the Mg-Si-Sn-based nanocomposite thermoelectric material has the advantages of low thermal conductivity of lattices, and good thermoelectricity performance, and can be widely used in the fields of spaceflight, national defense, automotives and the like.

The invention relates to an n-type Mg3Sb2 alloy thermoelectric material and a preparation method thereof. The chemical formula of the alloy thermoelectric material is YxMg3.05-xSbBi, wherein x is greater than or equal to 0.002 and less than or equal to 0.03; the method is characterized by comprising the steps of taking high-purity simple substance as a raw material; proportioning according to the stoichiometric ratio in the chemical formula; carrying out vacuum packaging on a tantalum tube, high-temperature melting, annealing and heat treatment; cutting into pieces with the size of 3 mm; and performing vacuum hot-pressing sintering and slowly cooling to obtain the alloy thermoelectric material. Compared with the prior art, the method has the advantages that doping of the yttrium is improved by carrying out solid-solution on magnesium bismuthide, anion electrons are introduced, so that the carrier concentration and the lattice heat conductivity can be simultaneously regulated and controlled, and meanwhile, the content of magnesium oxide in the grain boundary of the N-type Mg3Sb2 alloy is reduced by utilizing tantalum packaging smelting, so that the high migration rate is achieved.

The invention relates to a novel GeSbTe compound thermoelectric material having a high concentration vacancy and a preparation method thereof, wherein the thermoelectric material has a chemical formula of Ge1-xSb2x/3Te, x is greater than 0 and less than or equal to 0.14; by using the high purity element as raw material, the novel GeSbTe compound thermoelectric material is obtained through grindinginto powder, vacuum hot pressing sintering and slow cooling after vacuum encapsulation, high temperature melting, and annealing heat treatment by dosing according to the stoichiometric ratio in the chemical formula. Compared with the prior art, the introduction of cationic vacancies enables simultaneous regulation of carrier concentration and lattice thermal conductivity. This simple and controllable technique may be widely applied to various thermoelectric materials, especially the materials with a large number of intrinsic defects, which provides a new approach to improving thermoelectric performance.

A three-dimensional net-shaped high thermal conductivity graphite framework structure comprises at least two layers of graphite heat conduction films (12) and is characterized in that the number of connection points between every two adjacent layers of the graphite heat conduction films (12) is more than 5, and the distance between the every two connection points is more than 1mm. The thermal conductivity of the graphite heat conduction films (12) is 400-2400W/mK, and the thickness of each graphite heat conduction film (12) is 5-100 microns. The three-dimensional net-shaped high thermal conductivity graphite framework structure has very high thermal conductivity on the three-dimensional direction, and heat conduction materials have high thermal conductivity and strong mechanical strength. The requirement of fast heat conduction can be met, and the design requirement of a certain mechanical structure can be met. The three-dimensional net-shaped high thermal conductivity graphite framework structure can serve as a framework to be used with other materials in a compound mode, and whole thermal conductivity is improved.

The invention discloses a NbFeSb-based high-entropy thermoelectric material, a preparation method thereof and application thereof. The chemical formula of the NbFeSb-based high-entropy thermoelectricmaterial is Nb1-xMxFeSb1-ySny, x=0.1 to 0.8, y=0 to 0.3, and M comprises any 4 to 5 elements in V, Ti, Hf, Zr, Sc, Y, Ta and Mo elements. The preparation method comprises the steps of weighing and taking pure metal raw materials according to a stoichiometric ratio of the elements contained in the NbFeSb-based high-entropy thermoelectric material and carrying out melting and annealing treatment anddischarge plasma sintering. The NbFeSb-based high-entropy thermoelectric material of the invention has a low lattice thermal conductivity. The process conditions of the preparation method of the NbFeSb-based high-entropy thermoelectric material are easy to control, the stability of microtopography and physicochemical properties of the prepared NbFeSb-based high-entropy thermoelectric material areensured, the efficiency of preparation is high, and the production cost is reduced.

The invention discloses a method for preparing a (Bi0.8Sb0.2)2Te3 nano thermoelectric material. The method comprises the following steps of (1) mixing a Bi2Te3 powder material and a Sb2Te3 powder material, and performing mechanical alloying treatment, thereby obtaining a ball-milling material; (2) taking a small part of ball-milling material, putting the ball-milling material into an alumina burning boat of a vacuum atmosphere furnace, filling mixed gas of argon and hydrogen, raising the temperature for performing vapor deposition, and collecting a powder material deposited on an alumina plate, thereby obtaining a vapor deposition material; (3) mixing the ball-milling material and the vapor deposition material according to a mass ratio of 5:1, and performing high-frequency heating and rapid hot press molding, thereby obtaining the (Bi0.8Sb0.2)2Te3 nano thermoelectric material. According to the preparation method, the electronic state density nearby a Fermi level is improved and controlled, and a Seebeck coefficient of the thermoelectric material is improved. Moreover, with nano-scale micro-defects, a scattering effect on phonons is enhanced, the lattice thermal conductivity of the thermoelectric material is reduced, and the thermoelectric performance of the material is greatly improved.

The invention relates to an N-type antimonous trimagnetite scandium-doped alloy thermoelectric material and a preparation method thereof. The chemical formula of the thermoelectric material is Mg<3.05-x>Sc<x>Sb<2-y>Bi<y>, wherein y is greater than 0 and less than or equal to 1, and x is greater than 0 and less than or equal to 0.03. Compared with the prior art, cationic electrons are introduced byimproving scandium doping through the solid solution of bismuth trimagnetite, so that carrier concentration and lattice thermal conductivity are regulated and controlled at the same time; the contentof magnesium oxide in the grain boundary of N-type Mg3Sb<2> alloy is reduced through tantalum packaging smelting, so that high mobility is shown. The simple and controllable technology can be widelyapplied to various thermoelectric materials, especially materials with a large number of intrinsic defects, and therefore, a new method is provided for improving thermoelectric performance.

The invention discloses a method for improving the multi-value storage characteristic of an In2Se3 phase change material. The method comprises the following steps: constructing crystal models of an alpha phase and a beta phase of In2Se3; respectively replacing tetrahedral In atoms and octahedral In atoms in the alpha phase with Sc in proportion to form an alpha-phase tetrahedral doping system model and an octahedral doping system model; replacing the octahedral In atoms in the beta phase with Sc in proportion to form a beta-phase octahedral doping system model; establishing models of elementalIn and elemental Sc; optimizing the model; calculating the doping formation energy of the alpha phase and the beta phase; calculating the total energy, the state density, the energy band structure and the elastic constant of the optimization model; calculating the electrical conductivity and the electronic thermal conductivity; calculating the relationship between the lattice thermal conductivityand the temperature; and comparing the thermal conductivity and the electrical conductivity before and after doping to obtain the phase change material with better performance. Metal elements meetinga certain condition are doped into the metal oxide, so the storage performance of the metal oxide can be improved.

The invention relates to a high-performance PbTe-based N-type thermoelectric material and preparation thereof. The chemical formula of the thermoelectric material is CuxPbTe0.75Se0.25, wherein x is greater than 0 and less than or equal to 0.75%. Compared with the prior art, by using heterovalent interstitial copper atom doping, electrons can be released at interstitial positions after copper atomsenter crystal lattices, and the carrier concentration is adjusted, so that the material shows the properties of an N-type semiconductor. Due to the fact that the added interstitial copper atoms havethe solubility which is continuously increased along with the temperature in a PbTe0.75Se0.25 material system, the carrier concentration which is increased along with the temperature rise can be obtained in the temperature rise process, dynamic optimization of the carrier concentration is achieved, and the electrical transport performance of the material is enhanced. Besides, high-density intragranular dislocations can be introduced into the material due to aggregation of the interstitial copper atoms, and remarkable lattice strain can be introduced into the material due to the dislocation defects, so that the lattice thermal conductivity of the material is greatly reduced, and the thermal performance of the material is greatly optimized.

The invention relates to the technical field of thermoelectric materials and discloses a SiO2 nanoparticle composite cage compound thermoelectric material and a preparation method thereof. In the invention, 50 to 300 nanometer SiO2 nanoparticles are mixed with a cage compound, the regulation of the electron transport performance of the cage compound thermoelectric material and the considerable reduction of lattice thermal conductivity are realized by adding a proper amount of the SiO2 nanoparticles, and finally the hermoelectric property of the cage compound thermoelectric material is improved. In addition, the preparation method of the SiO2 nanoparticle composite cage compound thermoelectric material is simple and easy to implement, overcomes the drawbacks of introducing other impurities easily and preventing the mixed second-phase particles from dispersing and agglomeration easily of the traditional preparation method, and makes the nano SiO2 particles uniformly dispersed and mixed with the cage compound thermoelectric material.

The invention discloses a ZrNiSn-based high-entropy thermoelectric material and a preparation method and application thereof. The chemical formula of the ZrNiSn-based high-entropy thermoelectric material is Zr<1>-<x>M<x>Ni<1>-<y>Co<y>Sn<1>-<z>Sb<z>, wherein x=0.2-0.8, y=0-0.2, and z=0-0.3; and M comprises any 4-5 elements of V, Nb, Hf, Ti, Sc, Y, Ta and Mo. The preparation method comprise the steps that all pure metal raw materials are weighed and taken according to the stoichiometric ratio of the elements contained by the ZrNiSn-based high-entropy thermoelectric material, and the steps of smelting treatment, annealing treatment and discharging plasma sintering are conducted. The ZrNiSn-based high-entropy thermoelectric material has the low lattice thermal conductivity; the technological condition of the preparation method of the ZrNiSn-based high-entropy thermoelectric material is easy to control, stability of microstructure and physicochemical properties of the prepared ZrNiSn-basedhigh-entropy thermoelectric material is ensured, the preparation efficiency is high, and the production cost is reduced.

The invention discloses a novel Zint1 phase thermoelectric material. The chemical formula of the novel Zintl phase thermoelectric material is YbMg2Sb2, the novel Zintl phase thermoelectric material isa pure-phase hexagonal crystal structure, the width of a forbidden band calculated by the energy band structure is 1.23 eV, the YbMg2Sb2 thermoelectric material is doped with Na, the chemical formulais Yb1-xNaxMg2Sb2, Mg2Sb2, and x is greater than or equal to 0 and less than or equal to 0.025. Na is doped at the position of Yb, so that the concentration of carriers is increased, and meanwhile, the thermal conductivity of lattices is reduced, the thermoelectric performance is improved, and the highest thermoelectric optimal value is reached when the temperature is 77K. The novel Zintl phase thermoelectric material is prepared, the electricity and the heat transportation performance are optimized simultaneously through Na doping, and the novel Zintl phase thermoelectric material has an application potential. The development of the Zintl phase thermoelectric material is promoted.