CN114408874B - Bismuth telluride thermoelectric material based on entropy engineering and preparation method thereof - Google Patents

Bismuth telluride thermoelectric material based on entropy engineering and preparation method thereof Download PDF

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CN114408874B
CN114408874B CN202210033342.8A CN202210033342A CN114408874B CN 114408874 B CN114408874 B CN 114408874B CN 202210033342 A CN202210033342 A CN 202210033342A CN 114408874 B CN114408874 B CN 114408874B
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sintering
thermoelectric material
bismuth telluride
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CN114408874A (en
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何佳清
朱彬
王江舵
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Shenzhen Thermoelectricity New Energy Technology Co ltd
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    • C01B19/00—Selenium; Tellurium; Compounds thereof
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    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/547—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on sulfides or selenides or tellurides
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
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    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
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    • H10N10/852—Thermoelectric active materials comprising inorganic compositions comprising tellurium, selenium or sulfur
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    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/66—Specific sintering techniques, e.g. centrifugal sintering
    • C04B2235/666—Applying a current during sintering, e.g. plasma sintering [SPS], electrical resistance heating or pulse electric current sintering [PECS]

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Abstract

The invention provides a bismuth telluride thermoelectric material based on entropy engineering and a preparation method thereof, wherein the chemical formula of the bismuth telluride thermoelectric material is Bi 2‑x‑z Q z Sb x Te 3‑y Se y The method comprises the steps of carrying out a first treatment on the surface of the Wherein Q comprises any one or a combination of at least two of Ag, cu or Cr; x is more than 0 and less than 2, y is more than 0 and less than 3, and z is more than 0 and less than or equal to 0.1. According to the bismuth telluride thermoelectric material, the high-performance room-temperature thermoelectric material is obtained through entropy engineering, on one hand, electron is provided by doping of Q element, and electric conductivity is optimized, on the other hand, as a plurality of elements are in solid solution, the configuration entropy of the material is remarkably increased, the material becomes more stable, a single-phase material is obtained, and the non-harmonicity is remarkably enhanced due to the increase of the configuration entropy, so that the lattice thermal conductivity is greatly reduced; the thermoelectric property of the bismuth telluride thermoelectric material is obviously improved due to synchronous optimization of the electric and thermal transport characteristics.

Description

Bismuth telluride thermoelectric material based on entropy engineering and preparation method thereof
Technical Field
The invention belongs to the technical field of energy materials, relates to a thermoelectric material and a preparation method thereof, and particularly relates to a bismuth telluride thermoelectric material based on entropy engineering and a preparation method thereof.
Background
The thermoelectric material is a new energy material capable of directly realizing the mutual conversion of heat energy and electric energy, and the mechanism is established on the three thermoelectric conversion effects of the Seebeck effect, the Peltier effect and the Thomson effect. As energy problems have received increasing attention over the past decades, research into thermoelectric materials has therefore entered a new stage. The thermoelectric refrigerating and generating device can be manufactured by utilizing the P-type semiconductor thermoelectric material and the N-type semiconductor thermoelectric material to be connected in series. The thermoelectric device has the advantages of no pollution, no noise, no moving parts, no vibration and the like. The conversion efficiency of thermoelectric devices is mainly dependent on the dimensionless thermoelectric figure of merit of the material：ZT＝(α 2 Sigma/kappa) T, where alpha is the seebeck coefficient, sigma is the electrical conductivity, kappa is the thermal conductivity, and T is the thermodynamic temperature. Clearly, an ideal thermoelectric material should have high electrical properties and low thermal conductivity, but the increase in ZT values is challenging due to the interrelation of these physical parameters.
High performance thermoelectric devices require that the thermoelectric properties and service temperature areas of the P-type and N-type materials be matched to each other as much as possible. Bismuth telluride is the thermoelectric material with the best performance and the most widely commercialized application near the room temperature at present. The ZT value of the current P-type bismuth telluride alloy and the current N-type bismuth telluride alloy both reach about 1.4, but the performance of the current P-type bismuth telluride alloy still cannot meet the increasingly vigorous market, and the commercial application of the current P-type bismuth telluride alloy and the current N-type bismuth telluride alloy is severely limited.
CN112500164a discloses a bismuth telluride thermoelectric material and a preparation method thereof, the preparation method comprises: step one, according to the chemical formula X of the N-type bismuth telluride material w /Bi 2 Te 2.7-w Se 0.3 Weighing Bi, te and Se simple substance powder as raw materials, or according to chemical formula X of the P-type bismuth telluride material w /Bi 0.5-w Sb 1.5 Te 3 Weighing Bi, sb and Te simple substance powder as raw materials, wherein X is doping element, w is the stoichiometric ratio of the doping element X, and the range is more than or equal to 0 and less than or equal to 0.1; step two, uniformly mixing the raw materials, and then placing the mixture in a ball milling tank provided with a plasma generator for high-energy ball milling; transferring the powder in the tank body after ball milling to a sintering mold under inert gas for sintering, wherein the sintering is performed twice, and cooling to obtain the bismuth telluride thermoelectric material. The method for preparing the high-performance bismuth telluride material by combining the plasma ball milling and spark plasma sintering technology for the first time has the advantages of high speed, controllable powder components, low energy consumption and suitability for mass production.
CN110752285a discloses a method for improving the performance of N-type Bi-Sb-Te-Se based thermoelectric materials, comprising the following steps: according to chemical formula Bi 2-x Sb x Te 3-y Se y Weighing metal particles in the stoichiometric ratio of each element in Te of + zwt% as raw materials, and mixing and smelting to obtain a master alloy, wherein x is more than or equal to 0 and less than or equal to 2, y is more than or equal to 0 and less than or equal to 3, and z is more than or equal to 0 and less than or equal to 30; placing the master alloy into a vacuum ball mill to ball-mill into nanoscale powder, wherein the nanoscale powder isComprises Bi 2-x Sb x Te 3-y Se y Multiphase material with Te; sintering the nanoscale powder into a block by using a spark plasma sintering technology to obtain the N-type Bi-Sb-Te-Se-based thermoelectric material, wherein the sintering temperature in the spark plasma sintering technology is higher than the melting point of Te phase and lower than Bi 2-x Sb x Te 3-y Se y Is a melting point of (c). According to the manufacturing method for improving the performance of the N-type Bi-Sb-Te-Se-based thermoelectric material, the mother alloy is ball-milled through a ball milling process, and the thermoelectric performance of the N-type Bi-Sb-Te-Se-based thermoelectric material is improved through sintering nano-scale powder obtained after ball milling through a liquid phase sintering technology.
Currently, researchers combine entropy engineering with thermoelectric materials, and it is desirable to develop high performance thermoelectric materials. In 2004, the concept of "high-entropy alloy" was proposed, and Cantor et al prepared a single-phase multicomponent alloy with stable configuration entropy for the first time, and thereafter, high-entropy engineering was widely studied in the alloy field. Until 2015, entropy-stabilized oxide (Mg 0.2 Zn 0.2 Co 0.2 Cu 0.2 Zn 0.2 ) After O is reported, the high entropy concept is stepping into the ceramic domain. The method not only confirms the driving force of entropy, but also opens up a new idea for researching the high-entropy nonmetallic material. High entropy systems typically have four major high entropy effects: thermodynamically high entropy effects; kinetically a delayed diffusion effect; structurally, a lattice distortion effect; is a cocktail effect in performance. Through reasonable formula design, the high-entropy material with high strength, high hardness, giant dielectric constant, high-temperature oxidation resistance and low thermal conductivity can be obtained. Unlike high entropy alloys, high entropy ceramics are typically semiconductors or insulators with a band gap, which makes them potentially functional materials. For example, high entropy copper-based compounds can be good thermoelectric materials due to their large seebeck coefficient and low thermal conductivity.
In summary, the invention provides the bismuth telluride thermoelectric material based on entropy engineering and the preparation method thereof.
Disclosure of Invention
In view of the problems in the prior art, the present invention provides an entropy-based engineeringBismuth telluride thermoelectric material and preparation method thereof, wherein the chemical formula of the bismuth telluride thermoelectric material is Bi 2-x-z Q z Sb x Te 3-y Se y The method comprises the steps of carrying out a first treatment on the surface of the Wherein Q comprises any one or a combination of at least two of Ag, cu or Cr; x is more than 0 and less than 2, y is more than 0 and less than 3, and z is more than 0 and less than or equal to 0.1. According to the bismuth telluride thermoelectric material, the high-performance room-temperature thermoelectric material is obtained through entropy engineering, on one hand, electron is provided by doping of Q element, and electric conductivity is optimized, on the other hand, as a plurality of elements are in solid solution, the configuration entropy of the material is remarkably increased, the material becomes more stable, a single-phase material is obtained, and the non-harmonicity is remarkably enhanced due to the increase of the configuration entropy, so that the lattice thermal conductivity is greatly reduced; the thermoelectric property of the bismuth telluride thermoelectric material is obviously improved due to synchronous optimization of the electric and thermal transport characteristics; the preparation method disclosed by the invention is simple in process, only comprises smelting, grinding and sintering, and is convenient for large-scale popularization.
To achieve the purpose, the invention adopts the following technical scheme:
one of the purposes of the invention is to provide an entropy engineering-based bismuth telluride thermoelectric material, which has a chemical formula as follows: bi (Bi) 2-x-z Q z Sb x Te 3-y Se y ；
Wherein Q comprises any one or a combination of at least two of Ag, cu or Cr; x is more than 0 and less than 2, y is more than 0 and less than 3, and z is more than 0 and less than or equal to 0.1.
According to the bismuth telluride thermoelectric material, the high-performance room-temperature thermoelectric material is obtained through entropy engineering, on one hand, electron is provided by doping of Q element, and electric conductivity is optimized, on the other hand, as a plurality of elements are in solid solution, the configuration entropy of the material is remarkably increased, the material becomes more stable, a single-phase material is obtained, and the non-harmonicity is remarkably enhanced due to the increase of the configuration entropy, so that the lattice thermal conductivity is greatly reduced; the thermoelectric property of the bismuth telluride thermoelectric material is obviously improved due to synchronous optimization of the electric and thermal transport characteristics.
The bismuth telluride thermoelectric material based on entropy engineering obtains the high-performance room temperature thermoelectric material through entropy engineering, and greatly reduces lattice heat conductivity by utilizing the increase of entropy on the basis of maintaining better electric transmission, so that the high-performance room temperature thermoelectric material is obtained, and a new way is provided for refrigeration and power generation application of the thermoelectric material near room temperature.
Aiming at the problem of lower performance of bismuth telluride alloy of the traditional room temperature thermoelectric material, the stable high-entropy single-phase room temperature thermoelectric material is obtained by an entropy increasing method, so that the non-harmonicity is greatly increased, the lattice heat conductivity is reduced, and meanwhile, the carrier concentration is optimized by doping external atoms, so that the high-performance room temperature thermoelectric material is obtained.
It should be noted that, in the chemical formula of the bismuth telluride thermoelectric material based on entropy engineering according to the present invention, x is 0 < x < 2, for example, 0.1, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3, 1.4, or 1.7, etc., but not limited to the listed values, and other non-listed values in the above-mentioned numerical ranges are equally applicable.
It should be noted that, in the chemical formula of the bismuth telluride thermoelectric material based on entropy engineering according to the present invention, y satisfies 0 < y < 3, for example, 0.1, 0.5, 0.8, 0.9, 1, 1.3, 1.6, 1.7, 2, 2.2, 2.4, 2.5, 2.7 or 2.9, etc., but not limited to the listed values, and other non-listed values in the above-mentioned numerical ranges are equally applicable.
It should be noted that, in the chemical formula of the bismuth telluride thermoelectric material based on entropy engineering according to the present invention, z is more than 0 < z and less than or equal to 0.1, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, etc., but not limited to the listed values, and other non-listed values in the above-mentioned numerical ranges are equally applicable.
The second object of the invention is to provide a preparation method of the bismuth telluride thermoelectric material based on entropy engineering, which comprises the following steps:
(1) According to the chemical formula Bi 2-x-z Q z Sb x Te 3-y Se y Weighing a simple substance of Bi, a simple substance of Q, a simple substance of Sb, a simple substance of Te and a simple substance of Se according to the stoichiometric ratio; wherein Q comprises any one or a combination of at least two of Ag, cu or Cr, x is more than 0 and less than 2, y is more than 0 and less than 3, and z is more than 0 and less than or equal to 0.1; will weighThe raw materials are uniformly mixed and sequentially smelted and cooled to obtain master alloy;
(2) Grinding the master alloy obtained in the step (1) to obtain sample powder;
(3) And (3) sintering the sample powder obtained in the step (2) to obtain the bismuth telluride thermoelectric material based on entropy engineering.
The preparation method only comprises smelting, grinding and sintering, and has the advantages of simple process, strong practicability, convenience for large-scale popularization and the like.
It is worth to say that the purity of each raw material in the preparation method is above 99.99 wt%.
In the step (1), the weighed raw materials are filled into a quartz tube, sealed and uniformly mixed, and then put into a muffle furnace for smelting, and the master alloy is obtained after cooling.
As a preferable technical scheme of the invention, the vacuum degree of the sealed quartz tube is controlled to be (5-9) multiplied by 10 - 4 Pa, e.g. 5X 10 -4 Pa、5.5×10 -4 Pa、6×10 -4 Pa、6.5×10 -4 Pa、7×10 -4 Pa、7.5×10 -4 Pa、8×10 - 4 Pa、8.5×10 -4 Pa or 9X 10 -4 Pa, etc., but is not limited to the recited values, and other values not recited in the above-described numerical ranges are equally applicable.
In a preferred embodiment of the present invention, the temperature rise rate of the smelting in the step (1) is 2 to 5 ℃/min, for example, 2 ℃/min, 2.5 ℃/min, 3 ℃/min, 3.8 ℃/min, 4 ℃/min, 4.2 ℃/min, 4.7 ℃/min or 5 ℃/min, etc., but the invention is not limited to the recited values, and other non-recited values within the above-recited ranges are applicable.
It is worth to say that, in the process of smelting each weighed raw material to obtain the master alloy, if the temperature rising speed is too low and is lower than 2 ℃/min, the structure of the final material is coarse, and the performance of the thermoelectric material is affected; if the temperature rising speed is too high and is higher than 5 ℃/min, each raw material particle is heated unevenly in a muffle furnace, so that the particle smelting is insufficient, and the obtained master alloy possibly contains a heterogeneous phase, and the heterogeneous phase can influence the performance of the thermoelectric material. The preparation method controls the heating rate within the range of [2 ℃/min,5 ℃/min ], so that the particles can be fully smelted, and coarse tissues can be avoided.
Preferably, the smelting temperature in step (1) is 850-1050 ℃, for example 850 ℃, 875 ℃, 900 ℃, 925 ℃, 950 ℃, 960 ℃, 975 ℃, 990 ℃, 995.5 ℃, 1000 ℃, 1010 ℃, 1020 ℃, 1030 ℃, 1040 ℃,1050 ℃, etc., but is not limited to the values listed, and other values not listed in the above-mentioned value ranges are equally applicable.
It is worth noting that in the process of smelting each weighed raw material to obtain a master alloy, if the smelting temperature is too low and is lower than 850 ℃, insufficient smelting of each raw material particle can be caused, and the obtained master alloy possibly contains a heterogeneous phase, and the heterogeneous phase can influence the performance of the thermoelectric material; if the smelting temperature is too high, above 1050 ℃, it may lead to explosions during the smelting of the individual raw material particles. The preparation method controls the smelting temperature within the range of [850 ℃,1050 ℃ and the like, so that each raw material particle can be fully smelted, and the problem of explosion in the smelting process can be avoided.
Preferably, the heat-preserving time of the smelting in the step (1) is 2-10h, for example, 2h, 2.5h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, etc., but not limited to the listed values, and other non-listed values in the above-mentioned value range are equally applicable.
It is worth noting that, in the process of smelting each weighed raw material to obtain a master alloy, if the heat preservation time is too short and shorter than 2 hours, insufficient smelting of particles can be caused, and the obtained master alloy possibly contains a heterogeneous phase, and the heterogeneous phase can influence the performance of the thermoelectric material; if the holding time is too long, longer than 10 hours, explosion may occur in the process of smelting the particles. The preparation method controls the heat preservation time of smelting within the range of [2h,10h ], so that particles can be fully smelted, and the problem of explosion in the smelting process can be avoided.
In the step (2), the master alloy obtained in the step (1) is put into a grinding tank for manual grinding.
Preferably, the milling pot comprises an agate milling pot or a stainless steel milling pot.
As a preferred embodiment of the present invention, the grinding time in the step (2) is 0.5-5h, for example, 0.5h, 0.55h, 0.6h, 0.64h, 0.72h, 0.77h, 0.8h, 0.86h, 0.93h, 0.99h, 1h, 2h, 2.5h, 3h or 5h, etc., but not limited to the recited values, and other non-recited values within the above range are equally applicable.
It should be noted that, in the process of grinding the master alloy to obtain sample powder, if the grinding time is too short and shorter than 0.5h, the particle size of the obtained sample powder will be too large; if the grinding time is too long and longer than 5 hours, the possibility of oxidation reduction of the master alloy is increased, and the obtained sample powder may be doped with a mixed phase, and the mixed phase may affect the performance of the thermoelectric material. The preparation method controls the grinding time within the range of [0.5h,5h ], so that the master alloy can be fully ground, and the doping of impurity phases in sample powder obtained by grinding can be avoided.
Preferably, the sample powder of step (2) has a particle size in the range of 300-400. Mu.m, i.e. after sieving, a sample powder having a particle size in the range of 300-400. Mu.m, e.g. 300. Mu.m, 310. Mu.m, 320. Mu.m, 325. Mu.m, 338. Mu.m, 350.9. Mu.m, 364. Mu.m, 370. Mu.m, 380. Mu.m, 390. Mu.m, 400. Mu.m, etc., is obtained, but not limited to the values listed, and other non-listed values within the above-mentioned values are equally applicable.
In the process of grinding the master alloy to obtain the sample powder, the particle size range of the sample powder obtained by sieving is defined to be [300 μm,400 μm ], and the sample powder does not have metallic luster, so that whether the sample powder is located within [300 μm,400 μm ] can be roughly judged by observing whether the surface of the sample powder obtained after grinding has metallic luster.
In a preferred technical scheme of the invention, the sintering in the step (3) is spark plasma sintering or hot press sintering.
In a preferred embodiment of the present invention, the sintering temperature in step (3) is 400 to 480 ℃, for example 400 ℃, 425 ℃, 450 ℃, 453 ℃, 455 ℃, 458 ℃, 460.2 ℃, 464 ℃, 470 ℃, 475 ℃, 478.6 ℃ or 480 ℃, etc., but the sintering temperature is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned numerical ranges are equally applicable.
It is worth to say that the preparation method of the invention controls the sintering temperature to be [400, 480 ], not only can obtain compact products, avoid influencing thermoelectric materials, but also can prevent explosion in the sintering process.
Preferably, the sintering pressure in step (3) is 40-60MPa, for example 40MPa, 43MPa, 45Pa, 46Pa, 49Pa, 50Pa, 52.5Pa, 55.3MPa, 55Pa, 57Pa, 58MPa or 60MPa, etc., but is not limited to the values recited, and other values not recited in the above ranges are equally applicable.
It is worth noting that, in the process of sintering the sample powder, if the sintering pressure is too low and is lower than 40MPa, the powder bonding degree is not high, and the performance of the thermoelectric material is affected; if the sintering pressure is too high, above 60MPa, explosion may occur during the sintering process. The preparation method controls the sintering pressure to be 40MPa and 60MPa, so that the powder combination degree can be improved, and explosion in the sintering process can be avoided.
Preferably, the sintering time in the step (3) is 3-8min, for example, 3min, 3.5min, 4min, 4.2min, 4.5min, 4.9min, 5min, 5.3min, 5.6min, 5.8min, 6min, 6.1min, 6.7min, 7min, 7.2min, 7.4min, 7.75min or 8min, but not limited to the recited values, and other non-recited values in the above range are equally applicable.
It should be noted that, in the process of sintering the sample powder, if the sintering time is too short and shorter than 3min, the sintering is insufficient, which affects the performance of the thermoelectric material; if the sintering time is too long and longer than 8 minutes, the grains are too large, so that the performance of the thermoelectric material is reduced. The preparation method controls the sintering time within the range of [3min,8min ], so that the powder can be fully sintered, and the performance of the thermoelectric material is not affected due to overlarge sintered grains.
As a preferable technical scheme of the invention, the preparation method comprises the following steps:
(1) According to the chemical formula Bi 2-x-z Q z Sb x Te 3-y Se y Weighing a simple substance of Bi, a simple substance of Q, a simple substance of Sb, a simple substance of Te and a simple substance of Se according to the stoichiometric ratio; wherein Q comprises any one or a combination of at least two of Ag, cu or Cr, x is more than 0 and less than 2, y is more than 0 and less than 3, and z is more than 0 and less than or equal to 0.1; filling the weighed raw materials into a quartz tube, sealing and uniformly mixing, putting into a muffle furnace for smelting, and cooling to obtain the master alloy;
wherein the vacuum degree of the sealed quartz tube is controlled to be (5-9) multiplied by 10 -4 Pa; controlling the heating rate of the smelting to be 2-5 ℃/min, the temperature to be 850-1050 ℃ and the heat preservation time to be 2-10h;
(2) Placing the master alloy obtained in the step (1) into an agate grinding tank or a stainless steel grinding tank, manually grinding for 0.5-5h, and sieving to obtain sample powder with the granularity range of 300-400 mu m;
(3) And (3) performing spark plasma sintering or hot-pressing sintering on the sample powder obtained in the step (2), wherein the sintering temperature is controlled to be 400-480 ℃, the pressure is controlled to be 40-60MPa, and the time is 3-8min, so that the bismuth telluride thermoelectric material based on entropy engineering is obtained.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) According to the bismuth telluride thermoelectric material, the high-performance room-temperature thermoelectric material is obtained through entropy engineering, on one hand, electron is provided by doping of Q element, and electric conductivity is optimized, on the other hand, as a plurality of elements are in solid solution, the configuration entropy of the material is remarkably increased, the material becomes more stable, a single-phase material is obtained, and the non-harmonicity is remarkably enhanced due to the increase of the configuration entropy, so that the lattice thermal conductivity is greatly reduced;
(2) The thermoelectric property of the bismuth telluride thermoelectric material is obviously improved due to synchronous optimization of the electric and thermal transport characteristics;
(3) The preparation method disclosed by the invention is simple in process, only comprises smelting, grinding and sintering, and is convenient for large-scale popularization.
Drawings
FIG. 1 is a graph showing comparison of thermoelectric figure of merit ZT with temperature change curves of thermoelectric materials obtained in examples 1 to 3 and comparative examples 1 to 2 according to the present invention.
Detailed Description
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings.
For a better illustration of the present invention, which is convenient for understanding the technical solution of the present invention, exemplary but non-limiting examples of the present invention are as follows:
example 1
The embodiment provides a bismuth telluride thermoelectric material based on entropy engineering and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) According to the chemical formula Bi 0.97 Ag 0.03 SbTe 2 The stoichiometric ratio of Se weighs the simple substances of Bi, ag, sb, te and Se; wherein Q is Ag, x=1, y=1, z=0.03; filling the weighed raw materials into a quartz tube, sealing and uniformly mixing, putting into a muffle furnace for smelting, and cooling to obtain the master alloy;
wherein the vacuum degree of the sealed quartz tube is controlled to be 7 multiplied by 10 -4 Pa; controlling the heating rate of the smelting to be 5 ℃/min, the temperature to be 1050 ℃, and the heat preservation time to be 6 hours;
(2) Placing the master alloy obtained in the step (1) into an agate grinding tank or a stainless steel grinding tank, manually grinding for 2 hours, and sieving to obtain sample powder with the granularity ranging from 300 mu m to 400 mu m;
(3) And (3) performing spark plasma sintering on the sample powder obtained in the step (2), wherein the sintering temperature is controlled to be 400 ℃, the pressure is controlled to be 40MPa, and the time is 8min, so that the bismuth telluride thermoelectric material based on entropy engineering is obtained.
Example 2
The embodiment provides a bismuth telluride thermoelectric material based on entropy engineering and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) According to the chemical formula Bi 0.95 Ag 0.05 SbTe 2 The stoichiometric ratio of Se weighs the simple substances of Bi, ag, sb, te and Se; wherein Q is Ag, x=1, y=1, z=0.05; filling the weighed raw materials into a quartz tube, sealing and uniformly mixing, putting into a muffle furnace for smelting, and cooling to obtain the master alloy;
wherein the vacuum degree of the sealed quartz tube is controlled to be 7 multiplied by 10 -4 Pa; controlling the heating rate of the smelting to be 3 ℃/min, the temperature to be 950 ℃ and the heat preservation time to be 6 hours;
(2) Placing the master alloy obtained in the step (1) into an agate grinding tank or a stainless steel grinding tank, manually grinding for 3 hours, and sieving to obtain sample powder with the granularity ranging from 300 mu m to 400 mu m;
(3) And (3) performing spark plasma sintering on the sample powder obtained in the step (2), wherein the sintering temperature is controlled to be 450 ℃, the pressure is controlled to be 50MPa, and the time is 5min, so that the bismuth telluride thermoelectric material based on entropy engineering is obtained.
Example 3
The embodiment provides a bismuth telluride thermoelectric material based on entropy engineering and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) According to the chemical formula Bi 0.94 Ag 0.06 SbTe 2 The stoichiometric ratio of Se weighs the simple substances of Bi, ag, sb, te and Se; wherein Q is Ag, x=1, y=1, z=0.06; filling the weighed raw materials into a quartz tube, sealing and uniformly mixing, putting into a muffle furnace for smelting, and cooling to obtain the master alloy;
wherein the vacuum degree of the sealed quartz tube is controlled to be 7 multiplied by 10 -4 Pa; controlling the heating rate of the smelting to be 2 ℃/min, the temperature to be 850 ℃ and the heat preservation time to be 6 hours;
(2) Placing the master alloy obtained in the step (1) into an agate grinding tank or a stainless steel grinding tank, manually grinding for 2 hours, and sieving to obtain sample powder with the granularity ranging from 300 mu m to 400 mu m;
(3) And (3) performing spark plasma sintering on the sample powder obtained in the step (2), wherein the sintering temperature is controlled to be 480 ℃, the pressure is controlled to be 60MPa, and the time is controlled to be 4min, so that the bismuth telluride thermoelectric material based on entropy engineering is obtained.
Comparative example 1
This comparative example provides a P-type Bi 2 Te 3 Thermoelectric material and method of making the same, the method of making comprising the steps of:
(1) According to the chemical formula Bi 2 Te 3 Weighing Bi simple substance and Te simple substance according to the stoichiometric ratio, filling the weighed raw materials into a quartz tube, sealing and uniformly mixing, putting into a muffle furnace for smelting, and cooling to obtain the master alloy;
wherein the vacuum degree of the sealed quartz tube is controlled to be 7 multiplied by 10 -4 Pa; controlling the heating rate of the smelting to be 3 ℃/min, the temperature to be 950 ℃ and the heat preservation time to be 6 hours;
(2) Placing the master alloy obtained in the step (1) into an agate grinding tank or a stainless steel grinding tank, manually grinding for 3 hours, and sieving to obtain sample powder with the granularity ranging from 300 mu m to 400 mu m;
(3) Performing spark plasma sintering on the sample powder obtained in the step (2), controlling the sintering temperature to be 450 ℃, the pressure to be 50MPa and the time to be 5min to obtain the P-type Bi 2 Te 3 Thermoelectric materials.
Comparative example 2
This comparative example provides a bismuth telluride thermoelectric material and a method of making the same, differing only in that based on the method of making described in example 2: step (1) omits Q (i.e., ag), the chemical formula is BiSbTe 2 Se, i.e., x=1, y=1; the preparation method comprises the following steps:
(1) According to the chemical formula BiSbTe 2 The stoichiometric ratio of Se weighs the simple substance of Bi, simple substance of Sb, simple substance of Te and simple substance of Se; filling the weighed raw materials into a quartz tube, sealing and uniformly mixing, putting into a muffle furnace for smelting, and cooling to obtain the master alloy;
wherein the vacuum degree of the sealed quartz tube is controlled to be 7 multiplied by 10 -4 Pa; controlling the heating rate of the smelting to be 3 ℃/min, the temperature to be 950 ℃ and the heat preservation time to be 6 hours;
(2) Placing the master alloy obtained in the step (1) into an agate grinding tank or a stainless steel grinding tank, manually grinding for 3 hours, and sieving to obtain sample powder with the granularity ranging from 300 mu m to 400 mu m;
(3) And (3) performing spark plasma sintering on the sample powder obtained in the step (2), wherein the sintering temperature is controlled to be 450 ℃, the pressure is controlled to be 50MPa, and the time is 5min, so that the bismuth telluride thermoelectric material based on entropy engineering is obtained.
Fig. 1 is a graph showing comparison of thermoelectric figure of merit ZT with temperature change curves of the thermoelectric materials obtained in examples 1-3 and comparative examples 1-2, as can be seen from fig. 1:
(1) The bismuth telluride thermoelectric material based on entropy engineering obtained in example 2 has thermoelectric figure of merit ZT greater than 1.2 when the temperature is at [350K,500K ], and reaches a maximum value of 1.7 when the temperature is at 425K;
(2) Although the thermoelectric figure of merit ZT of the entropy engineering-based bismuth telluride thermoelectric materials obtained in example 1 and example 3 was slightly decreased compared to example 2, the thermoelectric performance was still higher at temperatures at [350k,500k ];
(3) Comparative example 1P-type Bi 2 Te 3 The maximum value of the thermoelectric figure of merit ZT of the thermoelectric material is only 0.9, and the maximum value of the thermoelectric figure of merit ZT corresponding to the example 1 is 1.7, which is improved by 89% compared with the maximum value of the thermoelectric figure of merit ZT corresponding to the comparative example 1, which is 0.9;
(4) The bismuth telluride thermoelectric material obtained in comparative example 2 has a thermoelectric figure of merit ZT maximum value of only 0.5 due to the omission of the doping of the Q element, and the thermoelectric performance is greatly reduced.
In summary, the bismuth telluride thermoelectric material obtains the high-performance room temperature thermoelectric material through entropy engineering, on one hand, doping of Q element provides electrons to optimize electrical conductivity, and on the other hand, due to the fact that a large amount of elements are in solid solution, the configuration entropy of the material is remarkably increased, the material becomes more stable, a single-phase material is obtained, the non-harmonicity is remarkably enhanced due to the increase of the configuration entropy, and therefore lattice thermal conductivity is greatly reduced; the thermoelectric property of the bismuth telluride thermoelectric material is obviously improved due to synchronous optimization of the electric and thermal transport characteristics; the preparation method disclosed by the invention is simple in process, only comprises smelting, grinding and sintering, and is convenient for large-scale popularization.
The detailed structural features of the present invention are described in the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope of the present invention and the scope of the disclosure.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.

Claims (13)

1. The preparation method of the bismuth telluride thermoelectric material based on entropy engineering is characterized by comprising the following steps of:
(1) According to the chemical formula Bi 2-x-z Q z Sb x Te 3-y Se y Weighing a simple substance of Bi, a simple substance of Q, a simple substance of Sb, a simple substance of Te and a simple substance of Se according to the stoichiometric ratio; wherein Q comprises any one or a combination of at least two of Ag, cu or Cr, x is more than or equal to 0.7 and less than or equal to 2,0.8, y is more than or equal to 3,0.03 and less than or equal to z is more than or equal to 0.1; uniformly mixing the weighed raw materials, and sequentially smelting and cooling to obtain a master alloy; the temperature rising speed of the smelting is 2.5-5 ℃/min, the temperature is 925-1050 ℃, and the heat preservation time is 6-9h;
(2) Grinding the master alloy obtained in the step (1) to obtain sample powder;
(3) And (3) sintering the sample powder obtained in the step (2) to obtain the bismuth telluride thermoelectric material based on entropy engineering.
2. The preparation method according to claim 1, wherein in the step (1), the weighed raw materials are filled into a quartz tube, sealed and uniformly mixed, placed into a muffle furnace for smelting, and cooled to obtain the master alloy.
3. The method according to claim 2, wherein the vacuum degree of the sealed quartz tube is controlled to be (5-9). Times.10 -4 Pa。
4. The method according to claim 1, wherein in the step (2), the master alloy obtained in the step (1) is put into a grinding pot for manual grinding.
5. The method of claim 4, wherein the milling pot comprises an agate milling pot or a stainless steel milling pot.
6. The method of claim 1, wherein the milling in step (2) is performed for a period of 0.5 to 5 hours.
7. The method of claim 1, wherein the sample powder in step (2) has a particle size in the range of 300-400 μm.
8. The method of claim 1, wherein the sintering in step (3) is spark plasma sintering or hot press sintering.
9. The method of claim 1, wherein the sintering temperature in step (3) is 400-480 ℃.
10. The method according to claim 1, wherein the sintering pressure in step (3) is 40 to 60MPa.
11. The method of claim 1, wherein the sintering time in step (3) is 3-8min.
12. The preparation method according to claim 1, characterized in that the preparation method consists of the steps of:
(1) According to the chemical formula Bi 2-x-z Q z Sb x Te 3-y Se y Weighing a simple substance of Bi, a simple substance of Q, a simple substance of Sb, a simple substance of Te and a simple substance of Se according to the stoichiometric ratio; wherein Q comprises any one or a combination of at least two of Ag, cu or Cr, x is more than or equal to 0.7 and less than or equal to 2,0.8, y is more than or equal to 3,0.03 and less than or equal to z is more than or equal to 0.1; filling the weighed raw materials into a quartz tube, sealing and uniformly mixing, putting into a muffle furnace for smelting, and cooling to obtain the master alloy;
wherein the vacuum degree of the sealed quartz tube is controlled to be (5-9) multiplied by 10 -4 Pa; controlling the heating rate of the smelting to be 2.5-5 ℃/min, the temperature to be 925-1050 ℃ and the heat preservation time to be 6-9h;
(2) Placing the master alloy obtained in the step (1) into an agate grinding tank or a stainless steel grinding tank, manually grinding for 0.5-5h, and sieving to obtain sample powder with the granularity range of 300-400 mu m;
(3) And (3) performing spark plasma sintering or hot-pressing sintering on the sample powder obtained in the step (2), wherein the sintering temperature is controlled to be 400-480 ℃, the pressure is controlled to be 40-60MPa, and the time is 3-8min, so that the bismuth telluride thermoelectric material based on entropy engineering is obtained.
13. Bismuth telluride thermoelectric material based on entropy engineering, characterized in that it is obtained by the preparation method according to any one of claims 1-12.
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