CN112853151A - Thermoelectric material and preparation method thereof - Google Patents

Thermoelectric material and preparation method thereof Download PDF

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Publication number
CN112853151A
CN112853151A CN201911192591.6A CN201911192591A CN112853151A CN 112853151 A CN112853151 A CN 112853151A CN 201911192591 A CN201911192591 A CN 201911192591A CN 112853151 A CN112853151 A CN 112853151A
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powder
metal
temperature
pore
thermoelectric material
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姜恒
曹聪帅
聂革
房娟
耿金峰
齐会龙
魏彦存
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ENN Science and Technology Development Co Ltd
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ENN Science and Technology Development Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C12/00—Alloys based on antimony or bismuth
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/1003—Use of special medium during sintering, e.g. sintering aid
    • B22F3/1007—Atmosphere
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/11—Making porous workpieces or articles
    • B22F3/1121—Making porous workpieces or articles by using decomposable, meltable or sublimatable fillers
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/08—Alloys with open or closed pores
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon

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  • Mechanical Engineering (AREA)
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  • Metallurgy (AREA)
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  • Crystallography & Structural Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)

Abstract

The invention discloses a thermoelectric material and a preparation method thereof, and the method comprises the steps of putting metal simple substances with preset components and preset proportion into a graphite tube to prepare a metal ingot; grinding the metal ingot into powder; adding the powdery metal ingot into absolute ethyl alcohol in which 2-20 wt% of pore-forming agent is dissolved, and uniformly dispersing; drying the uniformly dispersed liquid to obtain powder; and sintering the powder in vacuum or inert gas atmosphere to obtain the p-type thermoelectric material containing the nano-pores. According to the method, a few-electron metal is placed in a graphite tube to prepare a metal ingot, a pore-forming agent and the powdery metal ingot are sintered together, nano pores are distributed in the sintered block material, electrons do not influence the passing of the nano pores, the phonon scattering at the boundary of the pores and the thermoelectric material is improved, the thermal conductivity of the material can be reduced, the phonon scattering of the P-type thermoelectric material is enhanced due to the existence of a plurality of pores, and the prepared P-type skutterudite with a multi-nano-pore structure is enabled to further improve the ZT value of the material.

Description

Thermoelectric material and preparation method thereof
Technical Field
The invention relates to the technical field of thermoelectric materials, in particular to a thermoelectric material and a preparation method thereof.
Background
With the gradual shortage of traditional energy sources such as coal, petroleum, natural gas and the like and the increasingly prominent contradiction between the traditional energy sources and environmental protection and ecological balance, the traditional energy sources face a series of unavoidable resource shortage and safety challenges, and further development of the society is restricted. The practical pressure of environmental pollution and energy shortage causes changes in energy structure, and development of novel and environmentally-friendly renewable energy and energy conversion technology becomes the strategic key point of future sustainable development of all countries in the world.
The thermoelectric material can realize the interconversion of thermal energy and electric energy. The thermoelectric cooling system is mainly applied to thermoelectric power generation and electric refrigeration. The thermoelectric generation has lower requirements on the quality of heat sources, such as waste heat of an automobile engine cover, waste heat of tail gas, industrial waste heat and the like. The thermoelectric material power generation device does not contain movable parts, is quiet, reliable and easy to maintain. In addition, it can also generate heat or refrigerate by electric energy. The refrigerator made of high-performance thermoelectric materials can gradually replace the traditional compression refrigerator, has the advantages of simple structure, small volume, no noise and the like, and has wide application prospect in the fields of energy conservation and environmental protection.
The quality of the thermoelectric material is judged by ZT value:
ZT＝S2σT/κ
the ZT value is mainly related to the Seebeck coefficient S, the electrical conductivity σ and the thermal conductivity κ, wherein S2σ is called the power factor. Good thermoelectric materials need to have high power factors and low thermal conductivity.
In a neutral thermoelectric material, the N-type thermoelectric material is obtained after the metal with multiple electrons is doped, the P-type thermoelectric material is obtained after the metal with few electrons is doped, the P-type thermoelectric material is obtained after the number of holes in the material is larger than the number of electrons, and the main current carrier of the N-type material is electrons, so that the effect of improving the conductivity of the material is more remarkable. To improve the energy conversion efficiency of the thermoelectric device, the P-type ZT value is close to the N-type ZT value, so that the development of the high-performance P-type skutterudite thermoelectric material has continuous requirements.
Disclosure of Invention
Objects of the invention
The invention aims to provide a thermoelectric material and a preparation method thereof, the method comprises the steps of placing a few electronic metals into a graphite tube to prepare a metal ingot, sintering a pore-forming agent and the powdered metal ingot together, wherein nano pores are distributed in the sintered bulk material, the existence of the nano pores does not influence the passing of electrons, the scattering of phonons at the boundary of the pores and the thermoelectric material is improved, the thermal conductivity of the material can be reduced, the phonon scattering of the P-type thermoelectric material is enhanced due to the existence of a plurality of pores, so that the prepared P-type skutterudite with a multi-nano-pore structure is obtained, and the ZT value of the material is further improved.
(II) technical scheme
In order to solve the above problems, a first aspect of the present invention provides a method for producing a thermoelectric material, comprising: placing metal simple substances with preset components and preset proportion into a graphite tube to prepare a metal ingot; grinding the metal ingot into powder; adding the powdery metal ingot into absolute ethyl alcohol in which 2-20 wt% of pore-forming agent is dissolved, and uniformly dispersing; drying the uniformly dispersed liquid to obtain powder; and sintering the powder in vacuum or inert gas atmosphere to obtain the p-type thermoelectric material containing the nano-pores.
Further, the step of placing a preset metal simple substance component and a preset proportion into the graphite tube to prepare the metal ingot comprises the following steps: placing a metal simple substance with preset components and a preset proportion into a graphite tube, and covering a graphite tube cap; placing a graphite tube containing a metal simple substance with preset components into a quartz tube, and necking the quartz tube containing the graphite tube; vacuumizing the quartz tube after necking, fusing the necking part, and sealing the graphite tube in the quartz tube after necking; carrying out melting treatment on the quartz tube sealed with the graphite tube; putting the quartz tube after the melting treatment into cold water for quenching treatment; and slowly heating the quenched quartz tube to a temperature lower than the melting temperature, and annealing to obtain the metal ingot.
Further, the temperature of the melting treatment is 900-1300 ℃, the time of the melting treatment is 10-30h, and the temperature rise rate of the melting treatment is 5-10 ℃/min.
Further, the temperature of the annealing treatment is 400-700 ℃.
Further, the grade of the particle size of the powder obtained by grinding the ingot is not higher than the micrometer level.
Further, after the metal ingot is ground into powder, before the metal ingot in powder form is added into anhydrous ethanol in which 2-20 wt% of pore-forming agent is dissolved and uniformly dispersed, the method further comprises the following steps: and putting the metal ingot powder into a solution containing a surfactant, and uniformly mixing.
Further, the temperature rise rate in the sintering process is 60-80 ℃/min. Preferably, in the sintering process, the heating rate is controlled to be 60-80 ℃/min; heating from room temperature at a rate of 60-80 deg.C/min; when the sintering temperature is 500 ℃, controlling the heating rate to be 10-15 ℃/min; when the sintering temperature is 650 ℃, controlling the heating rate to be 3-5%/min; when the sintering temperature reaches 660-750 ℃, the temperature is kept for 5-30 min.
Further, the pore-forming agent is one or more of adamantane, ammonium chloride and ferrocene.
Further, adding the powdery metal ingot into absolute ethyl alcohol in which 2-20 wt% of pore-forming agent is dissolved, and uniformly dispersing; wherein the pore-forming agent concentration range is 10%; and/or the volume ratio of the amount of the solution mixed into the pore-forming agent to the amount of the powder is 5:1-2: 1.
The second aspect of the present invention provides a thermoelectric material obtained by the production method provided in the first aspect, the thermoelectric materialThe chemical formula of the material is as follows: a. thexCo4-yFeySb12Wherein A is one or more of La, Ce, Pr, Ti, Ga, Ba, Nd and Ni, x is the mole fraction of any one doping element in A, y is the mole fraction of Fe, 0<x is less than or equal to 1 and 0<y<4。
(III) advantageous effects
The technical scheme of the invention has the following beneficial technical effects:
(1) the thermoelectric material provided by the embodiment of the invention is P-type skutterudite with a multi-nanopore structure, and phonon scattering of the P-type thermoelectric material is enhanced due to the existence of a plurality of pores, so that the ZT value of the material is further improved.
(2) According to the preparation method of the thermoelectric material provided by the embodiment of the invention, a small amount of electronic metal is placed in a graphite tube to prepare a metal ingot, a pore-forming agent and the powdered metal ingot are sintered together, nano pores are distributed in the sintered bulk material, the passing of electrons is not influenced by the existence of the nano pores, the phonon scattering at the boundary of the pores and the thermoelectric material is improved, the thermal conductivity of the material can be reduced, the phonon scattering of the P-type thermoelectric material is enhanced by the existence of a plurality of pores, so that the prepared P-type skutterudite with a multi-nano-pore structure is obtained, and the ZT value of the material is further improved.
Drawings
Fig. 1 is a schematic flow chart of a method for manufacturing a thermoelectric material according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
In the description of the present invention, it should be noted that the terms "first", "second", and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Fig. 1 is a schematic flow chart of a method for producing a thermoelectric material according to a first embodiment of the present invention.
As shown in fig. 1, the method for preparing the thermoelectric material includes steps S101 to S105:
step S101, placing metal simple substances with preset components into a graphite tube according to a preset proportion to prepare a metal ingot.
In one embodiment, the step of preparing the metal ingot by putting a predetermined elemental metal component into the graphite tube in a predetermined ratio includes steps S1011 to S1016.
Step S1011, placing the metal simple substances with the preset components into a graphite tube according to the preset proportion, and covering a graphite tube cap.
Specifically, the mass of a metal simple substance with preset components is calculated according to a preset metering ratio, the metal simple substance is weighed and placed in a graphite tube which is cleaned in advance, and then a graphite tube cap is covered. The metal simple substance can be one or more of La, Ce, Pr, Ti, Ga, Ba, Nd and Ni. Wherein the range of the mole fraction x of each of the above simple metals is 0< x ≦ 1.
More specifically, the metal simple substance with the preset composition is weighed according to a general formula of AxCo4-yFeySb12 according to a preset metering ratio, wherein A is one or more of doping elements La, Ce, Pr, Ti, Ga, Ba, Nd and Ni, x is the mole fraction of any one element in the doping elements A, y is the mole fraction of Fe, x is more than or equal to 1 and 0 is less than or equal to 4.
Step S1012, placing a graphite tube containing a metal simple substance having a predetermined composition into a quartz tube, and necking the quartz tube containing the graphite tube.
Specifically, graphite tubes filled with various elemental metals are placed in a quartz tube, and then the quartz tube is placed on a high-temperature flame for necking.
And S1013, vacuumizing the quartz tube after necking, fusing the necking part, and sealing the graphite tube in the quartz tube after necking.
Specifically, the quartz tube after necking down is vacuumized by using vacuum tube sealing equipment, the necking part is fused, and the graphite tube is sealed in the quartz tube.
In step S1014, the quartz tube sealed with the graphite tube is melted.
Specifically, the sealed quartz tube obtained in step S1013 is placed in a muffle furnace, slowly heated to a predetermined temperature, and held for a predetermined time. Wherein the preset time can be 10-30 h.
In one embodiment, the temperature of the melting treatment is 900-.
And step S1015, putting the quartz tube after the melting treatment into cold water for quenching treatment.
Specifically, the quartz tube obtained in step S1014 is taken out of the muffle furnace, quenched in water by quenching, taken out after the temperature of the muffle furnace is raised to the melting temperature, and taken out after the quartz tube is completely cooled.
And step S1016, slowly heating the quenched quartz tube to a temperature lower than the melting temperature, and annealing to obtain the metal ingot. Preferably, the temperature of the annealing treatment is 400-700 ℃.
Specifically, the quartz tube quenched in the step S1015 is placed in a muffle furnace, slowly heated to a temperature lower than the melting temperature, kept for 20-200h, naturally cooled to room temperature, and taken out.
Step S102, grinding the metal ingot into powder to obtain metal powder.
In a preferred embodiment, the ingot is ground to a particle size of the resulting powder that is not higher than micron size. Alternatively, the grinding may be performed by ball milling. When the particle size of the powder obtained by grinding is not higher than the micron level, the more grain boundaries of the material are generated, which makes phonon scattering stronger and lattice thermal conductivity lower.
Step S103, adding the metal powder into absolute ethyl alcohol in which 2-20 wt% of pore-forming agent is dissolved, and uniformly dispersing.
Specifically, the ground powder is added into absolute ethyl alcohol dissolved with 2-20 wt% of pore-forming agent, and the mixture is stirred and dispersed for 30-60min while ultrasonic treatment is carried out, so as to obtain uniformly dispersed liquid. Here, the concentration of the pore-forming agent may be 2 w%, 2.5 w%, 3 w%, 3.5 w%, 4 w%, 4.5 w%, 5 w%, 5.5 w%, 6 w%, 6.5 w%, 7 w%, 7.5 w%, 8 w%, 8.5 w%, 9 w%, 9.5 w%, 10 w%, 10.5 w%, 11 w%, 12 w%, 13 w%, 14 w%, 15 w%, 16 w%, 17 w%, 18 w%, 19 w%, 20 w%.
The concentration of the pore-forming agent has higher influence on the performance of the thermoelectric material, when the concentration of the contrast agent is more than 20 wt%, the attached pore-forming agent is larger, the pore diameter formed during sintering is too large, the interface can be reduced, the density of the material can be reduced, and the performance of the material can be reduced; less than 2 wt%, less pore-forming agent, and too small pore diameter formed during sintering, so that phonon scattering effect is reduced, and the ideal effect of reducing lattice thermal conductivity is not achieved.
In a preferred and most preferred embodiment of the present invention, the pore former concentration is 10 w%.
In a preferred embodiment, the pore-forming agent is one or more of adamantane, ammonium chloride and ferrocene.
In a preferred embodiment, the ratio between the amount of the solution into which the pore-forming agent is mixed and the amount of the powder is 5:1 to 2: 1. When the ratio of the amount of the solution of the pore-forming agent to the amount of the powder is greater than 5:1, the amount of the pore-forming agent attached to the surface of the particles is large, the pore diameter formed during sintering is too large, the interface is reduced, the density of the material is reduced, and the performance of the material is reduced; less than 2:1, the amount of pore-forming agent attached to the surface of the material particles is small, the pore diameter formed during sintering is too small, the phonon scattering effect is reduced, and the ideal effect of reducing the lattice thermal conductivity cannot be achieved.
And step S104, drying the uniformly dispersed liquid to obtain powder.
Specifically, the solution is placed in a constant-temperature drying oven for drying at the drying temperature of 50-60 ℃ until the sample is completely dried.
And S105, sintering the powder in vacuum or inert gas atmosphere to obtain the p-type thermoelectric material containing the nano-pores.
Specifically, the dried powder is collected and placed into a sintering mold, and pressure sintering is carried out under vacuum or inert gas atmosphere, so as to obtain the p-type thermoelectric material rich in the nano pores.
Preferably, the temperature rise rate in the sintering process is controlled to be 60-80 ℃/min, so that the pore-forming agent can be prevented from evaporating. If the temperature rise rate is lower than 60 ℃/min, the pore-forming agent is slowly evaporated, is easily sealed in the pores and cannot completely escape from the material. If the temperature rise rate is higher than 80 ℃/min, the evaporation rate of the pore-forming agent is too high, so that the phonon scattering effect is reduced, and the ideal effect of reducing the lattice thermal conductivity cannot be achieved.
In a preferred embodiment, the sintering process may be performed by a multi-step heating method.
Specifically, the method comprises the following steps: firstly, controlling the heating rate to be 60-80 ℃/min; when the sintering temperature is 500 ℃, controlling the heating rate to be 10-15 ℃/min; when the sintering temperature reaches 650 ℃, finally controlling the heating rate to be 3-5%/min; when the sintering temperature reaches 660-750 ℃, the temperature is kept for 5-30 min.
In a preferred embodiment, between step S102 and step S103, further comprising:
and S102-1, putting the metal ingot powder obtained by grinding into a solution containing a surfactant, and uniformly mixing. Optionally, ultrasound may be used to uniformly mix the metal ingot powder and the solution, so as to increase the surface energy of the powder and make the pore-forming agent more easily attached to the surface of the powder.
Optionally, the surfactant may be one or more of oleic acid, palmitic acid, stearic acid and stearic acid. The concentration range of the surfactant is 0.2% -1%.
In a second aspect of the invention, a thermoelectric material is also provided. Can be prepared by the method of the first embodiment, and has the chemical formula:
AxCo4-yFeySb12, wherein A is one or more of doping elements La, Ce, Pr, Ti, Ga, Ba, Nd and Ni, x is the mole fraction of any one element in the doping elements A, y is the mole fraction of Fe, and x is more than 0 and less than or equal to 1 and y is more than 0 and less than 4.
When x is 0< x ≦ 1, the greater the value of x, the higher the thermoelectric figure of merit of the thermoelectric material, that is, the higher the efficiency of converting thermal energy into electric energy, and when y is greater than 4, cobalt is not contained in the thermoelectric material, and further P-type skutterudite cannot be obtained.
The thermoelectric material is P-type skutterudite with a multi-nanopore structure, and phonon scattering of the P-type thermoelectric material is enhanced due to the existence of a plurality of pores, so that the ZT value of the material is improved.
The solution according to the invention will be discussed in detail below by way of different embodiments.
Example 1
The thermoelectric material is Sb12Co3FeGa0.1La0.6In this example, A is La and Ga, wherein the mole fraction x1 of La is 0.6, the mole fraction x2 of Ga is 0.1, and y is 1.
The preparation method of the thermoelectric material comprises the following steps:
weighing Sb, Co, Fe, Ga and La according to the molar ratio of 12:3:1:0.1:0.6, placing the weighed metals into a graphite tube, and vacuumizing to 10 DEG-4And after Pa, closing the quartz tube.
Slowly heating the mixed raw materials to 1100 ℃, melting and mixing for 30h, quenching, then slowly heating to 550 ℃, annealing for 150h, and cooling to room temperature. Taking out, grinding into powder, and sieving with 160 mesh sieve.
And (3) placing the ground powder into absolute ethyl alcohol containing 3% ferrocene, ultrasonically stirring for 30min, and then drying the liquid in a constant-temperature drying oven at 50 ℃. Putting the powder into a sintering mold, heating to 670 deg.C with spark plasma sintering equipment, pressurizing to 30Mpa, and maintaining the temperature for 20 min.
Example 2
The thermoelectric material is as follows: sb12Co2.8Fe1.2Ba0.01Nd0.7Ti0.1In this example, a is Ba, Nd and Ti, where the mole fraction x1 of Nd is 0.6, the mole fraction x2 of Ba is 0.01, the mole fraction of Ti is 0.1, and y is 1.2.
The preparation method comprises the following steps:
metal Sb, Co, Fe, Ba, Nd and Ti are mixed according to the mol ratio12:2.8:1.2:0.01:0.7:0.1, placing the mixture into a graphite tube, and vacuumizing to 10%-5And after Pa, closing the quartz tube.
Slowly heating the mixed raw materials to 1150 ℃, melting and mixing for 20h, quenching, slowly heating to 600 ℃, annealing for 100h, and cooling to room temperature.
Taking out, grinding into powder, and sieving with 200 mesh sieve. The ground powder was put in anhydrous ethanol containing 10% adamantane, stirred ultrasonically for 40min, and then the liquid was dried in a constant temperature drying oven at 55 ℃.
Putting the powder into a sintering mold, heating to 680 deg.C with hot-pressing sintering equipment, pressurizing to 40Mpa, and keeping the temperature for 15 min.
Example 3
The thermoelectric material is as follows: sb12Co3.2Fe0.8Ga0.1Ti0.1Pr0.8In this example, A is Ti, Ga and Pr, wherein the mole fraction x1 of Ti is 0.1, the mole fraction x2 of Ga is 0.1, the mole fraction x3 of Pr is 0.8, and y is 0.8.
The preparation method comprises the following steps:
metal Sb, Co, Fe, Ga, Ti and Pr are weighed according to the molar ratio of 12:3.2:0.8:0.1:0.1:0.8 and then are placed in a graphite tube, and the graphite tube is vacuumized to 10-5And after Pa, closing the quartz tube.
Slowly heating the mixed raw materials to 1200 ℃, melting and mixing for 15h, quenching, then slowly heating to 650 ℃, annealing for 50h, and cooling to room temperature.
Taking out, grinding into powder, and sieving with 180 mesh sieve. Placing the ground powder into absolute ethyl alcohol containing 15% ammonium chloride, ultrasonically stirring for 50min, and drying the liquid in a constant-temperature drying oven at 60 ℃.
Putting the powder into a sintering mold, heating to 660 deg.C with hot-pressing sintering equipment, pressurizing to 60Mpa, and keeping the temperature for 10 min.
Example 4
The thermoelectric material is as follows: sb12Co3.3Fe0.7Ba0.1Nd0.6Ce0.3In the present embodiment, A is Ba, Nd and Ce, wherein the mole fraction of Ba is 0.1, the mole fraction of Nd is 0.6, and the mole fraction of Ce is 00.3 and y is 0.7. The preparation method comprises the following steps:
metal Sb, Co, Fe, Ba, Nd and Ce are weighed according to the mol ratio of 12:3.3:0.7:0.1:0.6:0.3 and then placed in a graphite tube, and the graphite tube is vacuumized to 10-4And after Pa, closing the quartz tube.
Slowly heating the mixed raw materials to 1300 ℃, melting and mixing for 10h, quenching, slowly heating to 700 ℃, annealing for 30h, and cooling to room temperature.
Taking out, grinding into powder, and sieving with 200 mesh sieve.
And (3) placing the ground powder into absolute ethyl alcohol containing 20% ferrocene, ultrasonically stirring for 60min, and then drying the liquid in a constant-temperature drying oven at 60 ℃.
Putting the powder into a sintering mold, heating to 660 deg.C with hot-pressing sintering equipment, pressurizing to 70Mpa, and keeping the temperature for 30 min.
Comparative example 1
The thermoelectric material is as follows: sb12Co3FeGa0.1La0.6
The preparation method comprises the following steps:
weighing Sb, Co, Fe, Ga and La according to the molar ratio of 12:3:1:0.1:0.6, placing the weighed metals into a graphite tube, and vacuumizing to 10 DEG-4And after Pa, closing the quartz tube.
Slowly heating the mixed raw materials to 1100 ℃, melting and mixing for 30h, and then quenching. Taking out, grinding into powder, and sieving with 160 mesh sieve. Putting the powder into a sintering mold, heating to 670 deg.C with spark plasma sintering equipment, pressurizing to 30Mpa, and maintaining the temperature for 20 min.
Comparative example 2
The thermoelectric material is as follows: sb12Co2.8Fe1.2Ba0.01Nd0.7Ti0.1
The preparation method comprises the following steps: metal Sb, Co, Fe, Ba, Nd and Ti are mixed according to the mol ratio
12:2.8:1.2:0.01:0.7:0.1, placing the mixture into a graphite tube, and vacuumizing to 10%-5And after Pa, closing the quartz tube. Slowly heating the mixed raw materials to 1150 ℃, melting and mixing for 20 hours, and then quenching. Taking out, grinding into powder, and sieving with 200 mesh sieve. Charging the powder into a sintering moldHeating to 680 deg.C with hot-pressing sintering equipment, pressurizing to 40Mpa, and keeping the temperature for 15 min.
Comparative example 3
The thermoelectric material is as follows: sb12Co3.2Fe0.8Ga0.1Ti0.1Pr0.8
The preparation method comprises the following steps: metal Sb, Co, Fe, Ga, Ti and Pr are weighed according to the molar ratio of 12:3.2:0.8:0.1:0.1:0.8 and then are placed in a graphite tube, and the graphite tube is vacuumized to 10-5And after Pa, closing the quartz tube. Slowly heating the mixed raw materials to 1200 ℃, melting and mixing for 15h, and then quenching. Taking out, grinding into powder, and sieving with 180 mesh sieve. Putting the powder into a sintering mold, heating to 660 deg.C with hot-pressing sintering equipment, pressurizing to 60Mpa, and keeping the temperature for 10 min.
Comparative example 4
The thermoelectric material is as follows: sb12Co3.3Fe0.7Ba0.1Nd0.6Ce0.3
The preparation method comprises the following steps: metal Sb, Co, Fe, Ba, Nd and Ce are weighed according to the mol ratio of 12:3.3:0.7:0.1:0.6:0.3 and then placed in a graphite tube, and the graphite tube is vacuumized to 10-4And after Pa, closing the quartz tube. Slowly heating the mixed raw materials to 1300 ℃, melting and mixing for 10 hours, and then quenching. Taking out, grinding into powder, and sieving with 200 mesh sieve. Putting the powder into a sintering mold, heating to 660 deg.C with hot-pressing sintering equipment, pressurizing to 70Mpa, and keeping the temperature for 30 min.
The thermoelectric performance tests were performed on the skutterudite thermoelectric materials obtained in the above examples and comparative examples, wherein the seebeck coefficient and the electrical conductivity were measured by ZEM-3 testing equipment, and the thermal conductivity was measured by a linses LFA-500 laser thermal conductivity tester for thermal diffusivity of the skutterudite thermoelectric material, and then calculated according to k ═ λ ρ Cp, where k is the thermal conductivity, λ is the thermal diffusivity, ρ is the density, and Cp is the specific heat capacity. The results of the thermoelectric properties of the materials are shown in the following table. As can be seen from the table, the performance of the P-type skutterudite thermoelectric material with polyatomic doping and multiple nano holes obtained by the method provided by the embodiment of the application is obviously superior to that of the samples of comparative examples 1-4, and the ZT value is improved by 10% -20%.
Examples Temperature of Thermal conductivity Seebeck coefficient Resistivity of ZT value
Example 1 450 0.024 156 10.1 0.73
Comparative example 1 450 0.0251 150 9.8 0.66
Example 2 450 0.0236 160 9.9 0.79
Comparative example 2 450 0.0244 155 9.6 0.74
Example 3 450 0.0231 169 10.3 0.87
Comparative example 3 450 0.0246 159 9.7 0.77
Example 4 450 0.0234 162 10 0.81
Comparative example 4 450 0.0248 154 9.5 0.73
Therefore, when the P-type thermoelectric material is prepared by a solid phase doping method in the prior art, the obtained ZT value of the material is often influenced by multiple factors such as the preparation process, the doping concentration and the components, and the effect of improving the ZT value is difficult to achieve. In the preparation method of the thermoelectric material provided by the embodiment of the invention, the filling of the nano-pores is added, so that electrons can pass through the pores, and phonons are scattered at the pore boundaries, and then the effect of reducing the thermal conductivity without influencing the electrical conductivity is achieved, and the ZT value of the prepared P-type thermoelectric material is improved.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims (11)

1. A method of making a thermoelectric material, comprising:
placing metal simple substances with preset components into a graphite tube according to a preset proportion to prepare a metal ingot;
grinding the metal ingot into metal powder;
adding the metal powder into absolute ethyl alcohol dissolved with 2-20 wt% of pore-forming agent and uniformly dispersing;
drying the uniformly dispersed liquid to obtain powder;
and sintering the powder in vacuum or inert gas atmosphere to obtain the p-type thermoelectric material containing the nano-pores.
2. The method according to claim 1, wherein the step of preparing the metal ingot by placing the predetermined elemental metal components in the graphite tube in a predetermined ratio comprises:
placing a metal simple substance with preset components and a preset proportion into a graphite tube, and covering a graphite tube cap;
placing a graphite tube containing a metal simple substance with preset components into a quartz tube, and necking the quartz tube containing the graphite tube;
vacuumizing the quartz tube after necking, fusing the necking part, and sealing the graphite tube in the quartz tube after necking;
carrying out melting treatment on the quartz tube sealed with the graphite tube;
putting the quartz tube after the melting treatment into cold water for quenching treatment;
and slowly heating the quenched quartz tube to a temperature lower than the melting temperature, and annealing to obtain the metal ingot.
3. The production method according to claim 2,
the temperature of the melting treatment is 900-1300 ℃, the time of the melting treatment is 10-30h, and the heating rate of the melting treatment is 5-10 ℃/min.
4. The production method according to claim 2,
the temperature of the annealing treatment is 400-700 ℃.
5. The method according to any one of claims 2 to 4, wherein the grade of the particle size of the powder obtained by grinding the ingot is not higher than the micrometer grade.
6. The production method according to any one of claims 2 to 4,
after the metal ingot is ground into powder, before the metal ingot in powder form is added into absolute ethyl alcohol in which 2 wt% -20 wt% of pore-forming agent is dissolved and uniformly dispersed, the method also comprises the following steps:
and putting the metal ingot powder into a solution containing a surfactant, and uniformly mixing.
7. The production method according to any one of claims 2 to 4, wherein the temperature rise rate during sintering is 60 to 80 ℃/min.
8. The method of claim 7, wherein controlling the temperature increase rate to be 60-80 ℃/min during the sintering comprises:
heating from room temperature at a rate of 60-80 deg.C/min;
when the sintering temperature is 500 ℃, controlling the heating rate to be 10-15 ℃/min;
when the sintering temperature is 650 ℃, controlling the heating rate to be 3-5 ℃/min;
when the sintering temperature reaches 660-750 ℃, the temperature is kept for 5-30 min.
9. The preparation method according to any one of claims 2 to 4, wherein the pore-forming agent is one or more of adamantane, ammonium chloride and ferrocene.
10. The preparation method according to any one of claims 2 to 4, wherein a powdered ingot is added to absolute ethanol in which 2 to 20 wt% of a pore-forming agent is dissolved and uniformly dispersed; wherein the content of the first and second substances,
the pore-forming agent concentration range is 10 wt%; and/or
The volume ratio of the solution mixed with the pore-forming agent to the powder is 5:1-2: 1.
11. A thermoelectric material produced by the method according to any one of claims 1 to 10, having a chemical formula: a. thexCo4-yFeySb12Wherein, in the step (A),
a is one or more of doping elements La, Ce, Pr, Ti, Ga, Ba, Nd and Ni, x is the mole fraction of any one element in the doping elements A, y is the mole fraction of Fe, x is more than 0 and less than or equal to 1, and y is more than 0 and less than 4.
CN201911192591.6A 2019-11-28 2019-11-28 Thermoelectric material and preparation method thereof Pending CN112853151A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000252526A (en) * 1998-06-30 2000-09-14 Matsushita Electric Ind Co Ltd Skutterudite thermoelectric material, thermocouple and manufacture thereof
CN101656292A (en) * 2009-09-16 2010-02-24 北京科技大学 Preparation method for bismuth-tellurium nano-porous thermoelectric material
CN103811653A (en) * 2014-01-21 2014-05-21 燕山大学 Multi-cobalt p type skutterudite filled thermoelectric material and preparation method thereof
CN105936985A (en) * 2016-06-30 2016-09-14 东华大学 Preparing method of high-performance multi-sized nanostructure skutterudite material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000252526A (en) * 1998-06-30 2000-09-14 Matsushita Electric Ind Co Ltd Skutterudite thermoelectric material, thermocouple and manufacture thereof
CN101656292A (en) * 2009-09-16 2010-02-24 北京科技大学 Preparation method for bismuth-tellurium nano-porous thermoelectric material
CN103811653A (en) * 2014-01-21 2014-05-21 燕山大学 Multi-cobalt p type skutterudite filled thermoelectric material and preparation method thereof
CN105936985A (en) * 2016-06-30 2016-09-14 东华大学 Preparing method of high-performance multi-sized nanostructure skutterudite material

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Application publication date: 20210528