阅读说明：本技术 一种兼具高强度和高热电性能的碲化铋基材料及其制备方法 (Bismuth telluride-based material with high strength and high thermoelectric performance and preparation method thereof ) 是由 隋解和 秦海旭 蔡伟 于 2021-09-13 设计创作，主要内容包括：一种兼具高强度和高热电性能的碲化铋基材料及其制备方法,本发明涉及一种碲化铋基材料及其制备方法。本发明要解决现有碲化铋基材料特殊的层状结构使其力学性能差,切削加工困难的问题。兼具高强度和高热电性能的碲化铋基材料的化学通式为Bi-(0.4)Sb-(1.6)Te-(3-x)；方法：一、称取；二、制备铸锭；三、研磨；四、烧结。本发明用于兼具高强度和高热电性能的碲化铋基材料及其制备。(The invention discloses a bismuth telluride-based material with high strength and high thermoelectric property and a preparation method thereof, and relates to a bismuth telluride-based material and a preparation method thereof. The invention aims to solve the problems of poor mechanical property and difficult cutting processing of the existing bismuth telluride-based material due to the special layered structure. The chemical general formula of the bismuth telluride-based material with high strength and high thermoelectric property is Bi 0.4 Sb 1.6 Te 3‑x (ii) a The method comprises the following steps: firstly, weighing; secondly, preparing an ingot; thirdly, grinding; fourthly, sintering. The bismuth telluride-based material is used for preparing the bismuth telluride-based material with high strength and high thermoelectric performance.)

1. The bismuth telluride-based material with high strength and high thermoelectric property is characterized in that the chemical general formula of the bismuth telluride-based material with high strength and high thermoelectric property is Bi_0.4Sb_1.6Te_3-x，0.01≤x≤0.03。

2. The bismuth telluride-based material as defined in claim 1 having both high strength and high thermoelectric properties, wherein x is 0.02-0.03.

3. The bismuth telluride-based material as in claim 1 wherein x is 0.03.

4. The method for preparing a bismuth telluride-based material having both high strength and high thermoelectric properties as in claim 1, which comprises the steps of:

firstly, weighing:

in a glove box in an argon protective atmosphere, the chemical formula is Bi_0.4Sb_1.6Te_3-xWeighing Bi, Sb and Te according to the stoichiometric ratio, placing the weighed raw materials in a quartz tube, and vacuumizing the quartz tube to 10 DEG C^-2Sealing under Pa to obtain a sealed quartz tube; wherein x is more than or equal to 0.01 and less than or equal to 0.03;

secondly, preparing an ingot:

placing the sealed quartz tube in a box-type resistance furnace, heating the sealed quartz tube to 1073K-1123K within 4 h-5 h, then preserving heat for 8 h-10 h under the condition of 1073K-1123K, and finally slowly cooling along with the furnace to obtain an initial ingot;

thirdly, grinding:

smashing the initial cast ingot, placing the smashed initial cast ingot in a stainless steel ball milling tank, and carrying out high-energy ball milling for 2-4 h under the argon atmosphere to obtain nanoscale powder;

fourthly, sintering:

sintering for 4-8 min by using a discharge plasma sintering furnace under the conditions that the temperature is 650-700K and the pressure is 60-80 MPa to obtain the bismuth telluride-based material with high strength and high thermoelectric performance.

5. The method for preparing the bismuth telluride-based material with high strength and high thermoelectric property as claimed in claim 4, wherein x is 0.02-0.03 in the first step.

6. The method for preparing the bismuth telluride-based material with high strength and high thermoelectric property as claimed in claim 4, wherein in the second step, the sealed quartz tube is heated to 1073K for 4h, and then the temperature is kept for 8h to 10h under the condition of 1073K.

7. The method for preparing a bismuth telluride-based material having both high strength and high thermoelectric properties as claimed in claim 4, wherein the nanoscale powder in step three has a particle size of 20nm to 50 nm.

8. The preparation method of the bismuth telluride-based material with high strength and high thermoelectric performance as claimed in claim 4, wherein in the third step, a SPEX-8000M high energy ball mill is used, and the high energy ball mill is used for 2-4 h under the argon atmosphere.

9. The method for preparing the bismuth telluride-based material with high strength and high thermoelectric performance as claimed in claim 4, wherein the fourth step is to sinter the bismuth telluride-based material for 5-8 min in a discharge plasma sintering furnace at a temperature of 650-700K and a pressure of 70-80 MPa.

10. The method for preparing the bismuth telluride-based material with high strength and high thermoelectric performance as claimed in claim 4, wherein the fourth step is to sinter the bismuth telluride-based material for 5min in a spark plasma sintering furnace at 673K and 80 MPa.

Technical Field

The invention relates to a bismuth telluride-based material and a preparation method thereof.

Background

In the last 20 years, the thermoelectric performance of the bismuth telluride-based alloy is rapidly improved through microstructure regulation and energy band engineering, and large-scale commercial application in the field of solid-state refrigeration is successfully realized. Particularly, in recent years, thermoelectric devices have attracted attention in terms of micro refrigeration and functions because of their advantages such as no vibration, no noise, no need for auxiliary components, and long service life, and thus are expected to be applied to the fields of electronics, medicine, and the like. However, the special layered structure of the bismuth telluride-based material causes the bismuth telluride-based material to have poor mechanical properties and difficult cutting and processing, and is difficult to process into micron-sized or even submicron-sized materials required by micro devices, thereby limiting the further development of the micro thermoelectric devices. Therefore, the mechanical property of the bismuth telluride alloy is improved while the high thermoelectric property is obtained.

Disclosure of Invention

The invention provides a bismuth telluride-based material with high strength and high thermoelectric property and a preparation method thereof, aiming at solving the problems that the existing bismuth telluride-based material is poor in mechanical property and difficult to cut due to a special layered structure.

The chemical general formula of the bismuth telluride-based material with high strength and high thermoelectric property is Bi_0.4Sb_1.6Te_3-x，0.01≤x≤0.03。

A preparation method of a bismuth telluride-based material with high strength and high thermoelectric performance is carried out according to the following steps:

firstly, weighing:

in a glove box in an argon protective atmosphere, the chemical formula is Bi_0.4Sb_1.6Te_3-xWeighing Bi, Sb and Te according to the stoichiometric ratio, placing the weighed raw materials in a quartz tube, and vacuumizing the quartz tube to 10 DEG C^-2Sealing under Pa to obtain a sealed quartz tube; wherein x is more than or equal to 0.01 and less than or equal to 0.03;

secondly, preparing an ingot:

placing the sealed quartz tube in a box-type resistance furnace, heating the sealed quartz tube to 1073K-1123K within 4 h-5 h, then preserving heat for 8 h-10 h under the condition of 1073K-1123K, and finally slowly cooling along with the furnace to obtain an initial ingot;

thirdly, grinding:

smashing the initial cast ingot, placing the smashed initial cast ingot in a stainless steel ball milling tank, and carrying out high-energy ball milling for 2-4 h under the argon atmosphere to obtain nanoscale powder;

fourthly, sintering:

sintering for 4-8 min by using a discharge plasma sintering furnace under the conditions that the temperature is 650-700K and the pressure is 60-80 MPa to obtain the bismuth telluride-based material with high strength and high thermoelectric performance.

The invention has the beneficial effects that:

the invention reduces Bi_0.4Sb_1.6Te₃And the proportion of the Te is combined with high-energy ball milling to grind the smelting cast ingot into powder with the size of 20 nm-50 nm. At the moment, a large amount of residual stress exists in the powder, the secondary grain boundary annealing in the subsequent discharge plasma sintering process is driven, high-density nanometer twin crystals are constructed, and the material compression strength is improved from 188MPa to 264 MPa. Meanwhile, the average zT value of the material at 30-250 ℃ is also improved from 0.86 to 1.07, the synchronous improvement of thermoelectric property and mechanical property is realized, and the improvement of mechanical property can solve the problems of poor mechanical property and difficult cutting processing of the existing bismuth telluride based material due to the special layered structure.

The invention is used for the bismuth telluride-based material with high strength and high thermoelectric property and the preparation method thereof.

Drawings

FIG. 1 is a transmission electron micrograph of (a) Bi prepared in a comparative experiment_0.4Sb_1.6Te₃(b) Bi prepared in example III_0.4Sb_1.6Te_2.97；

FIG. 2 is a plot of selected area electron diffraction patterns, (c) selected area electron diffraction patterns near the interface of the two layered structure in FIG. 1(b), (d) selected area electron diffraction patterns within the single layered structure in FIG. 1 (b);

FIG. 3 shows Bi_0.4Sb_1.6Te_3-xGraph of the variation of the conductivity of the alloy with temperature, 1 is Bi prepared in example one_0.4Sb_1.6Te_2.99And 2 is Bi prepared in example two_0.4Sb_1.6Te_2.98And 3 is Bi prepared in example III_0.4Sb_1.6Te_2.97And 4 is Bi prepared by a comparative experiment_0.4Sb_1.6Te₃；

FIG. 4 shows Bi_0.4Sb_1.6Te_3-xThe Seebeck coefficient of the alloy varies with temperature, 1 is Bi prepared in the first embodiment_0.4Sb_1.6Te_2.99And 2 is Bi prepared in example two_0.4Sb_1.6Te_2.98And 3 is Bi prepared in example III_0.4Sb_1.6Te_2.97And 4 is Bi prepared by a comparative experiment_0.4Sb_1.6Te₃；

FIG. 5 shows Bi_0.4Sb_1.6Te_3-xThe variation of the alloy thermal conductivity with the temperature is shown in the graph; bi prepared in example one_0.4Sb_1.6Te_2.99And 2 is Bi prepared in example two_0.4Sb_1.6Te_2.98And 3 is Bi prepared in example III_0.4Sb_1.6Te_2.97And 4 is Bi prepared by a comparative experiment_0.4Sb_1.6Te₃；

FIG. 6 shows Bi_0.4Sb_1.6Te_3-xThe thermoelectric figure of merit of the alloy is plotted with the change of temperature;

FIG. 7 shows Bi_0.4Sb_1.6Te_3-xThe average thermoelectric merit figure of the alloy in the range of 30-250 ℃;

FIG. 8 shows Bi_0.4Sb_1.6Te_3-xStress-strain curve at room temperature for the alloy.

Detailed Description

The technical solution of the present invention is not limited to the specific embodiments listed below, and includes any combination of the specific embodiments.

The first embodiment is as follows: the chemical general formula of the bismuth telluride-based material with high strength and high thermoelectric property is Bi_0.4Sb_1.6Te_3-x，0.01≤x≤0.03。

The beneficial effects of the embodiment are as follows: this embodiment reduces Bi_0.4Sb_1.6Te₃And the proportion of the Te is combined with high-energy ball milling to grind the smelting cast ingot into powder with the size of 20 nm-50 nm. At the moment, a large amount of residual stress exists in the powder, the secondary grain boundary annealing in the subsequent discharge plasma sintering process is driven, high-density nanometer twin crystals are constructed, and the material compression strength is improved from 188MPa to 264MPa. Meanwhile, the average zT value of the material at 30-250 ℃ is also improved from 0.86 to 1.07, the synchronous improvement of thermoelectric property and mechanical property is realized, and the improvement of mechanical property can solve the problems of poor mechanical property and difficult cutting processing of the existing bismuth telluride based material due to the special layered structure.

The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: x is more than or equal to 0.02 and less than or equal to 0.03. The rest is the same as the first embodiment.

The third concrete implementation mode: this embodiment is different from the first or second embodiment in that: x is 0.03. The other is the same as in the first or second embodiment.

The fourth concrete implementation mode: the preparation method of the bismuth telluride-based material with high strength and high thermoelectric property is carried out according to the following steps:

firstly, weighing:

in a glove box in an argon protective atmosphere, the chemical formula is Bi_0.4Sb_1.6Te_3-xWeighing Bi, Sb and Te according to the stoichiometric ratio, placing the weighed raw materials in a quartz tube, and vacuumizing the quartz tube to 10 DEG C^-2Sealing under Pa to obtain a sealed quartz tube; wherein x is more than or equal to 0.01 and less than or equal to 0.03;

secondly, preparing an ingot:

placing the sealed quartz tube in a box-type resistance furnace, heating the sealed quartz tube to 1073K-1123K within 4 h-5 h, then preserving heat for 8 h-10 h under the condition of 1073K-1123K, and finally slowly cooling along with the furnace to obtain an initial ingot;

thirdly, grinding:

smashing the initial cast ingot, placing the smashed initial cast ingot in a stainless steel ball milling tank, and carrying out high-energy ball milling for 2-4 h under the argon atmosphere to obtain nanoscale powder;

fourthly, sintering:

sintering for 4-8 min by using a discharge plasma sintering furnace under the conditions that the temperature is 650-700K and the pressure is 60-80 MPa to obtain the bismuth telluride-based material with high strength and high thermoelectric performance.

The fifth concrete implementation mode: the fourth difference between this embodiment and the specific embodiment is that: in the first step, x is more than or equal to 0.02 and less than or equal to 0.03. The rest is the same as the fourth embodiment.

The sixth specific implementation mode: the present embodiment is different from the fourth or fifth embodiment in that: and in the second step, the sealed quartz tube is heated to 1073K in 4h, and then the temperature is kept for 8 h-10 h under the condition of 1073K. The other is the same as the fourth or fifth embodiment.

The seventh embodiment: this embodiment differs from one of the fourth to sixth embodiments in that: the particle size of the nano-grade powder in the third step is 20 nm-50 nm. The other is the same as one of the fourth to sixth embodiments.

The specific implementation mode is eight: this embodiment is different from one of the fourth to seventh embodiments in that: and in the third step, a SPEX-8000M high-energy ball mill is used for high-energy ball milling for 2-4 h under the condition of argon atmosphere. The rest is the same as the fourth to seventh embodiments.

The specific implementation method nine: this embodiment is different from the fourth to eighth embodiment in that: and in the fourth step, a discharge plasma sintering furnace is used for sintering for 5-8 min under the conditions that the temperature is 650-700K and the pressure is 70-80 MPa. The others are the same as the fourth to eighth embodiments.

The detailed implementation mode is ten: this embodiment is different from one of the fourth to ninth embodiments in that: and in the fourth step, a discharge plasma sintering furnace is used for sintering for 5min under the conditions that the temperature is 673K and the pressure is 80 MPa. The rest is the same as the fourth to ninth embodiments.

The following examples were used to demonstrate the beneficial effects of the present invention:

the first embodiment is as follows:

the chemical general formula of the bismuth telluride-based material with high strength and high thermoelectric property is Bi_0.4Sb_1.6Te_3-xX is 0.01, i.e. the chemical formula is Bi_0.4Sb_1.6Te_2.99；

The preparation method of the bismuth telluride-based material with high strength and high thermoelectric property comprises the following steps:

firstly, weighing:

in a glove box in an argon protective atmosphere, the chemical formula is Bi_0.4Sb_1.6Te_3-xWeighing Bi, Sb and Te according to the stoichiometric ratio, placing the weighed raw materials in a quartz tube, connecting the quartz tube with a vacuum mechanical pump, and vacuumizing the quartz tube to 10 DEG C^-2Sealing the quartz tube by using high-temperature flame below Pa to obtain a sealed quartz tube; x is 0.01;

secondly, preparing an ingot:

placing the sealed quartz tube in a box-type resistance furnace, heating the sealed quartz tube to 1073K in 4h, then preserving the heat for 10h under the condition of 1073K, and finally slowly cooling along with the furnace to obtain an initial ingot;

thirdly, grinding:

smashing the initial cast ingot, placing the smashed initial cast ingot in a stainless steel ball milling tank, and carrying out high-energy ball milling for 2 hours by using a SPEX-8000M high-energy ball mill under the condition of argon atmosphere to obtain nanoscale powder;

fourthly, sintering:

sintering for 5min by using a discharge plasma sintering furnace under the conditions of 673K temperature and 80MPa pressure to obtain the bismuth telluride-based material with high strength and high thermoelectric property.

The particle size of the nano-grade powder in the third step is 20 nm-50 nm.

Example two: the difference between the present embodiment and the first embodiment is: x is 0.02, i.e. the chemical formula is Bi_0.4Sb_1.6Te_2.98. The rest is the same as the first embodiment.

Example three: the difference between the present embodiment and the first embodiment is: x is 0.03, that is, the chemical formula is Bi_0.4Sb_1.6Te_2.97. The rest is the same as the first embodiment.

Comparative experiment: the difference between the present embodiment and the first embodiment is: x is 0, i.e. the chemical formula is Bi_0.4Sb_1.6Te₃. The rest is the same as the first embodiment.

FIG. 1 is a transmission electron micrograph,(a) bi prepared by comparative experiment_0.4Sb_1.6Te₃(b) Bi prepared in example III_0.4Sb_1.6Te_2.97(ii) a As can be seen, some layered structure may appear inside the material grains, and Bi_0.4Sb_1.6Te_2.97The number of the middle laminated structure is far higher than that of Bi_0.4Sb_1.6Te₃。

FIG. 2 is a plot of selected area electron diffraction patterns, (c) selected area electron diffraction patterns near the interface of the two layered structure in FIG. 1(b), (d) selected area electron diffraction patterns within the single layered structure in FIG. 1 (b); as can be seen, two sets of blobs representing the same structural information appear in the (c) diagram, while only one set appears in the (d) diagram. This shows typical twin diffraction spot characteristics, confirming that the layered structure in fig. 1 is twin, and the occurrence of high-density twin can significantly improve the mechanical properties of the material.

FIG. 3 shows Bi_0.4Sb_1.6Te_3-xGraph of the variation of the conductivity of the alloy with temperature, 1 is Bi prepared in example one_0.4Sb_1.6Te_2.99And 2 is Bi prepared in example two_0.4Sb_1.6Te_2.98And 3 is Bi prepared in example III_0.4Sb_1.6Te_2.97And 4 is Bi prepared by a comparative experiment_0.4Sb_1.6Te₃. As can be seen, σ for all samples showed a downward trend during the rise of the test temperature, showing typical degenerate semiconductor characteristics. Bi formulated according to standard stoichiometric ratios_0.4Sb_1.6Te₃The alloy has the lowest sigma and is 54.7 multiplied by 10 at room temperature³Sm^-1. On the basis, the sigma is gradually increased along with the increase of x, and can reach 135.3 multiplied by 10 at 303K³Sm^-1。

FIG. 4 shows Bi_0.4Sb_1.6Te_3-xThe Seebeck coefficient of the alloy varies with temperature, 1 is Bi prepared in the first embodiment_0.4Sb_1.6Te_2.99And 2 is Bi prepared in example two_0.4Sb_1.6Te_2.98And 3 is Bi prepared in example III_0.4Sb_1.6Te_2.97And 4 is comparison practicePrepared Bi_0.4Sb_1.6Te₃. As can be seen, the Seebeck coefficients of all the alloys are positive values, and the p-type conductivity characteristic of typical hole dominance is shown. At 30 ℃, the Te content is reduced to ensure that the Seebeck coefficient is from 253.2 mu VK^-1144.8 mu VK reduction^-1And a seebeck coefficient of from 158.1 μ VK at 250 ℃^-1Increasing to 175.6 mu VK^-1。

FIG. 5 shows Bi_0.4Sb_1.6Te_3-xThe variation of the alloy thermal conductivity with the temperature is shown in the graph; bi prepared in example one_0.4Sb_1.6Te_2.99And 2 is Bi prepared in example two_0.4Sb_1.6Te_2.98And 3 is Bi prepared in example III_0.4Sb_1.6Te_2.97And 4 is Bi prepared by a comparative experiment_0.4Sb_1.6Te₃. The Te content is reduced to ensure that the room temperature thermal conductivity is from 0.85Wm^-1K^-1Increased to 1.41Wm^-1K^-1(ii) a However, at 250 deg.C, the thermal conductivity is from 1.53Wm by reducing the Te content^-1K^-1Reduced to 1.26Wm^-1K^-1It is stated that Bi can be reduced by reducing the Te content_0.4Sb_1.6Te₃Thermal conductivity of the material in the higher temperature region.

FIG. 6 shows Bi_0.4Sb_1.6Te_3-xThe thermoelectric figure of merit of the alloy is plotted with the change of temperature; as can be seen, the ratio is compared with Bi_0.4Sb_1.6Te₃Although the thermoelectric figure of merit of the alloy is not improved after the Te content is reduced, the temperature corresponding to the highest point of the curve is improved from 50 ℃ to more than 100 ℃.

FIG. 7 shows Bi_0.4Sb_1.6Te_3-xThe average thermoelectric merit figure of the alloy in the range of 30-250 ℃. As can be seen from the graph, the average thermoelectric figure of merit increased by 1.07 and 1.06, respectively, after decreasing by 0.01 and 0.02 Te.

FIG. 8 shows Bi_0.4Sb_1.6Te_3-xStress-strain curve at room temperature for the alloy. As can be seen from the figure, the compressive strength of the material is improved from 188MPa to 264MPa, and the compressive strain is correspondingly improved to 5.2%.