P-type ab2x2 zintl phase thermoelectric material, preparation method and application thereof
By introducing lattice engineering into p-type Zintl phase thermoelectric materials, a solid solution with zero crystal field splitting energy is formed, which solves the problem of low valence band degeneracy, improves carrier transport and reduces thermal conductivity, and enhances the thermoelectric performance of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2023-11-06
- Publication Date
- 2026-05-15
AI Technical Summary
Existing p-type Zintl phase thermoelectric materials have low valence band degeneracy and large effective mass per band, resulting in low zT values and making it difficult to achieve a balance between electrothermal transport.
By solid-solution of Mg3Sb2 with YbZn2Sb2, CaZn2Sb2, or YbCd2Sb2, a solid solution with zero crystal field splitting energy is formed, which increases band degeneracy and reduces the effective mass of a single band, thus optimizing electrothermal transport.
The zT value of the p-type AB2X2 type Zintl phase thermoelectric material was significantly improved, the carrier transport capacity was enhanced, the thermal conductivity was reduced, and the material exhibited excellent thermoelectric performance in the medium and high temperature range.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of thermoelectric materials technology, specifically to a class of p-type AB2X2 type Zintl phase thermoelectric materials, their preparation methods and applications. Background Technology
[0002] Thermoelectric materials enable the conversion of thermal energy into electrical energy, and have important applications in waste heat recovery, solid-state refrigeration, and deep space exploration. The energy conversion efficiency of thermoelectric materials depends on their dimensionless thermoelectric figure of merit. zT, zT = S 2 σT / κ , in S The Seebeck coefficient is... σ For electrical conductivity, κ Thermal conductivity, T This refers to absolute temperature. S2σ This is called the power factor. PF This determines the electrical properties of the material. An ideal thermoelectric material must achieve a balance between electrical and thermal transport to ensure... zT Maximize the value.
[0003] Zintl phase materials are a class of compounds that contain both ionic and covalent bond structures. The diverse chemical compositions of these compounds provide a high degree of freedom and tunability for modular crystal structure, thereby optimizing electroacoustic transport and thus attracting increasing attention. In particular, AB2X2 type (A = Mg, Ca, Sr, Ba, Yb, or Eu; B = Mg, Zn, Mn, Cd; X = Bi or Sb) exhibit excellent thermoelectric properties. For example, in n-type Mg3Sb2-based materials, the conduction band has high valley degeneracy (…). Nv =6) and low thermal conductivity, optimal zT The value can reach 1.7-1.9 at 773K.
[0004] The valence band structure of AB2X2 is mainly composed of the X atom. p Orbital contribution, due to p The track is z and x / y Inequivalent hybridization in direction, VBM (Valance Band Maximum) splits into nondegenerate forms. p z-orbitals and double degeneracy p x / p y orbit, p z and p x / p There is an energy shift between y and y, which is called the crystal field splitting energy ( ΔHowever, due to the low valence band degeneracy in most p-type Zintl phase materials (…), Nv =1) and single-band effective mass The majority of p-type Zintl phases zT The value is still very low. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a class of p-type AB2X2-type Zintl phase thermoelectric materials, their preparation methods, and applications. We propose a lattice engineering method to effectively decouple the electroacoustic transport of AB2X2-type Zintl phase thermoelectric materials by splitting the crystal field into positively charged Mg3Sb2 ( Δ <0) and YbZn2Sb2 or CaZn2Sb2 or YbCd2Sb2 with negative crystal field splitting energy. Δ >0) solid solution, forming a crystal field splitting energy of zero ( Δ Solid solutions with a mass ratio of 0 (=0) increase band degeneracy while decreasing the effective mass per band. This greatly promotes carrier transport. In addition, the thermal conductivity of the crystal lattice is significantly suppressed by phonon scattering caused by lattice distortion. Thanks to the synergistic optimization effect of electrothermal transport, the thermoelectric properties of the material are improved.
[0006] The first aspect of this invention provides a type of p-type AB2X2-type Zintl phase thermoelectric material, wherein the chemical formula of the p-type AB2X2-type Zintl phase thermoelectric material is Mg 3-3x Zn 2x Yb x Sb2 or Mg 3-3x Zn 2x Ca x Sb2 or Mg 3-3x Cd 2x Yb x Sb2, where x = 0.6~0.8.
[0007] The second aspect of this invention provides a method for preparing the above-mentioned p-type AB2X2-type Zintl phase thermoelectric material, comprising the following steps:
[0008] Weigh the elemental solids according to the stoichiometric ratio of the chemical formula of the p-type AB2X2 type Zintl phase thermoelectric material; place the weighed elemental solids in a ball milling device under an inert atmosphere and perform high-energy ball milling treatment.
[0009] The powder after high-energy ball milling was sintered to obtain p-type AB2X2 type Zintl phase thermoelectric material.
[0010] In one embodiment, the elemental solid comprises at least one of the following: magnesium granules with a purity of 99.95 wt% to 99.999 wt%, antimony granules with a purity of 99.99 wt% to 99.999 wt%, zinc powder with a purity of 99.9 wt% to 99.99 wt%, ytterbium powder with a purity of 99.9 wt% to 99.99 wt%, cadmium powder with a purity of 99.9 wt% to 99.99 wt%, and calcium blocks with a purity of 99.9 wt% to 99.99 wt%.
[0011] In one embodiment, the inert atmosphere is an argon atmosphere.
[0012] In one embodiment, the ball-to-material ratio of the high-energy ball milling process is 5:1 to 10:1, the rotation speed of the high-energy ball milling process is 1200 to 1500 revolutions per minute, and the high-energy ball milling process time is 10 to 15 hours.
[0013] In one embodiment, the sintering method is discharge plasma sintering, the sintering mold is a graphite mold, the sintering temperature is 550~650℃, the sintering pressure is 50~60MPa, and the sintering time is 3~6 minutes.
[0014] The third aspect of the present invention provides the application of the above-mentioned p-type AB2X2-type Zintl phase thermoelectric material in thermoelectric devices.
[0015] In one embodiment, the thermoelectric device includes a thermoelectric power generation device or a thermoelectric cooling device in the medium-to-high temperature range. Compared with the prior art, the present invention has the following beneficial effects:
[0016] 1. The p-type AB2X2 type Zintl phase thermoelectric material provided by the present invention is obtained by using Mg3Sb2( Δ <0) and YbZn2Sb2 or CaZn2Sb2 or YbCd2Sb2 ( Δ >0) Solid solution effectively alters the band structure while reducing the effective mass of a single band. This greatly promotes carrier transport, and the thermal conductivity of the lattice is significantly suppressed by phonon scattering caused by lattice distortion. Thanks to the synergistic effect of electrothermal transport, the thermoelectric properties of p-type AB2X2-type Zintl phase thermoelectric materials can be effectively improved. zT value.
[0017] 2. The Seebeck coefficient and conductivity of the p-type AB2X2 type Zintl phase thermoelectric material provided by this invention do not change monotonically with increasing temperature. The trend of conductivity changes when the temperature is 350K-450K. At the same time, the carrier concentration in the thermoelectric material increases with increasing solid solution content, while the thermal conductivity decreases with increasing solid solution content. This makes its optimal thermoelectric figure of merit reach about 1.0 at 750K, which has good thermoelectric performance.
[0018] 3. The preparation method of p-type AB2X2-type Zintl phase thermoelectric material provided by the present invention uses raw materials that are abundant, low in cost, and have simple production processes and equipment with good controllability and repeatability.
[0019] 4. The thermoelectric figure of merit of the p-type AB2X2 type Zintl phase thermoelectric material provided by the present invention zT At 750K, it has significant advantages over similar materials and can be used in thermoelectric power generation or thermoelectric refrigeration devices in the medium and high temperature range. It can be used for precision machining to prepare thermoelectric devices of various shapes and sizes. For example, in automobile exhaust and industrial production, especially in the metallurgical industry, it can be used to generate electricity by utilizing its high-temperature waste heat. This can achieve the effective utilization of low-density heat sources and achieve the goal of energy conservation and emission reduction to a certain extent. Attached Figure Description
[0020] Figure 1 The thermoelectric compound Mg obtained in Examples 1-9 3-3x Zn 2x Ca x Sb2, Mg 3-3x Zn 2x Yb x Sb2, Mg 3- 3x Cd 2x Yb x Sb2 (x = 0.6–0.8) and the thermoelectric compound Mg3Sb2 in Comparative Example 1 and the thermoelectric compounds Mg in Comparative Examples 2 and 3 3-3x Cd 2x Yb x X-ray diffraction (XRD) patterns of Sb2 (x=0.4 and 0.9) powders;
[0021] Figure 2 The thermoelectric compound Mg in Examples 1-3 3-3x Zn 2x Ca x The thermoelectric properties of Sb2 (x=0.6~0.8) and the thermoelectric compound Mg3Sb2 in Comparative Example 1, wherein, Figure 2 (a) is the electrical conductivity of the thermoelectric compound; Figure 2(b) is the Seebeck coefficient of the thermoelectric compound; Figure 2 (c) is the thermal conductivity of the thermoelectric compound, and Figure 2 (d) is the thermoelectric figure of merit of the thermoelectric compound. zT ;
[0022] Figure 3 It is the thermoelectric compound Mg in Examples 4-6 3-3x Zn 2x Yb x The thermoelectric properties of Sb2 (x=0.6~0.8) and the thermoelectric compound Mg3Sb2 in Comparative Example 1, wherein, Figure 3 (a) is the electrical conductivity of the thermoelectric compound; Figure 3 (b) is the Seebeck coefficient of the thermoelectric compound; Figure 3 (c) is the thermal conductivity of the thermoelectric compound, and Figure 3 (d) is the thermoelectric figure of merit of the thermoelectric compound. zT .
[0023] Figure 4 The thermoelectric compound Mg in Examples 7-9 3-3x Cd 2x Yb x Sb2 (x = 0.6–0.8) and the thermoelectric compound Mg in Comparative Examples 2 and 3 3-3x Cd 2x Yb x The thermoelectric properties of Sb2 (x=0.4 and 0.9), among which, Figure 4 (a) is the electrical conductivity of the thermoelectric compound; Figure 4 (b) is the Seebeck coefficient of the thermoelectric compound; Figure 4 (c) is the thermal conductivity of the thermoelectric compound, and Figure 4 (d) is the thermoelectric figure of merit of the thermoelectric compound. zT . Detailed Implementation
[0024] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.
[0025] This invention provides a class of p-type AB2X2-type Zintl phase thermoelectric materials, their preparation methods, and applications. The chemical formula of this material is Mg. 3-3x Zn 2x Yb x Sb2 or Mg 3-3x Zn 2x Ca xSb2 or Mg 3-3x Cd 2x Yb x Sb2, where x = 0.6~0.8. This material has broad application prospects in thermoelectric devices, especially in thermoelectric power generation or thermoelectric refrigeration devices in the medium and high temperature range. Specifically, it can be used for precision machining to prepare thermoelectric devices of various shapes and sizes. For example, in automobile exhaust and industrial production, especially in the metallurgical industry, its high-temperature waste heat can be used for power generation, which can realize the effective utilization of low-density heat sources and achieve the goal of energy conservation and emission reduction to a certain extent.
[0026] Next, the preparation method of the above-mentioned p-type AB2X2-type Zintl phase thermoelectric material will be explained:
[0027] The preparation method of the p-type AB2X2 type Zintl phase thermoelectric material provided by this invention is as follows: Elemental solids are weighed according to the stoichiometric ratio of the p-type AB2X2 type Zintl phase thermoelectric material. The weighed elemental solids are placed in a ball mill under an inert atmosphere and subjected to high-energy ball milling. The powder obtained after high-energy ball milling is sintered to obtain the p-type AB2X2 type Zintl phase thermoelectric material. The raw materials used in the above preparation method are abundant and inexpensive. The production process and equipment are simple, and the controllability and repeatability are good.
[0028] In some embodiments, the elemental solid includes at least one of the following: magnesium granules with a purity of 99.95 wt% to 99.999 wt%, antimony granules with a purity of 99.99 wt% to 99.999 wt%, zinc powder with a purity of 99.9 wt% to 99.99 wt%, ytterbium powder with a purity of 99.9 wt% to 99.99 wt%, cadmium powder with a purity of 99.9 wt% to 99.99 wt%, and calcium blocks with a purity of 99.9 wt% to 99.99 wt%.
[0029] In some implementations, the inert atmosphere is an argon atmosphere.
[0030] In some embodiments, the ball-to-material ratio of the high-energy ball milling process is 5:1 to 10:1, the rotation speed of the high-energy ball milling process is 1200 to 1500 rpm, and the high-energy ball milling process time is 10 to 15 hours.
[0031] In some embodiments, the sintering method is discharge plasma sintering, the sintering mold is a graphite mold, the sintering temperature is 550~650℃, the sintering pressure is 50~60MPa, and the sintering time is 3~6 minutes.
[0032] The present invention will be further explained in detail below with reference to embodiments:
[0033] Example 1 This example provides a p-type AB2X2 type Zintl phase thermoelectric material with the chemical formula Mg 1.2 Zn 1.2 Ca 0.6 Sb2.
[0034] In this embodiment, the chemical formula is Mg 1.2 Zn 1.2 Ca 0.6 The preparation method of Sb2 p-type AB2X2 type Zintl phase thermoelectric material is as follows:
[0035] The elemental solid raw materials Mg, Zn, Ca, and Sb are arranged according to Mg 1.2 Zn 1.2 Ca 0.6 The Sb2 was weighed according to its stoichiometric ratio. Then, the elemental solid raw material and stainless steel balls were placed in an argon atmosphere glove box and put into a stainless steel ball mill jar with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0036] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0037] The Mg obtained in this embodiment 1.2 Zn 1.2 Ca 0.6 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0038] The Mg obtained in this embodiment 1.2 Zn 1.2 Ca 0.6 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-750K) are... zT Values such as Figure 2 As shown.
[0039] Example 2
[0040] This embodiment provides a p-type AB2X2 type Zintl phase thermoelectric material with the chemical formula Mg. 0.9 Zn 1.4 Ca 0.7 Sb2.
[0041] In this embodiment, the chemical formula is Mg 0.9 Zn 1.4 Ca 0.7 The preparation method of Sb2 p-type AB2X2 type Zintl phase thermoelectric material is as follows:
[0042] The elemental solid raw materials Mg, Zn, Ca, and Sb are arranged according to Mg 0.9 Zn 1.4 Ca 0.7 The Sb2 was weighed according to its stoichiometric ratio, and then the elemental solid raw material and stainless steel balls were... Argon A stainless steel ball mill jar is placed in an atmospheric glove box with a ball-to-material ratio of 10:1, and then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0043] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0044] The Mg obtained in this embodiment 0.9 Zn 1.4 Ca 0.7 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0045] The Mg obtained in this embodiment 0.9 Zn 1.4 Ca 0.7 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-750K) are... zT Values such as Figure 2 As shown.
[0046] Example 3
[0047] This embodiment provides a p-type AB2X2 type Zintl phase thermoelectric material with the chemical formula Mg. 0.6 Zn 1.6 Ca 0.8 Sb2.
[0048] In this embodiment, the chemical formula is Mg 0.6 Zn 1.6 Ca 0.8 The preparation method of Sb2 p-type AB2X2 type Zintl phase thermoelectric material is as follows:
[0049] The elemental solid raw materials Mg, Zn, Ca, and Sb are arranged according to Mg 0.6 Zn 1.6 Ca 0.8 The Sb2 was weighed according to its stoichiometric ratio. Then, the elemental solid raw material and stainless steel balls were placed in an argon atmosphere glove box and put into a stainless steel ball mill jar with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0050] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0051] The Mg obtained in this embodiment 0.6 Zn 1.6 Ca 0.8 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0052] The Mg obtained in this embodiment 0.6 Zn 1.6 Ca 0.8 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-750K) are... zT Values such as Figure 2 As shown.
[0053] Example 4
[0054] This embodiment provides a p-type AB2X2 type Zintl phase thermoelectric material with the chemical formula Mg. 1.2 Zn 1.2 Yb 0.6 Sb2.
[0055] In this embodiment, the chemical formula is Mg 1.2 Zn 1.2 Yb 0.6 The preparation method of Sb2 p-type AB2X2 type Zintl phase thermoelectric material is as follows:
[0056] The elemental solid raw materials Mg, Zn, Yb, and Sb are arranged according to Mg 1.2 Zn 1.2 Yb 0.6 The Sb2 was weighed according to its stoichiometric ratio, and then the elemental solid and stainless steel balls were placed in a stainless steel ball mill jar in an argon atmosphere glove box with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0057] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0058] The Mg obtained in this embodiment 1.2 Zn 1.2 Yb 0.6 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0059] The Mg obtained in this embodiment 1.2 Zn 1.2 Yb 0.6 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-750K) are... zT Values such as Figure 3 As shown.
[0060] Example 5
[0061] This embodiment provides a p-type AB2X2 type Zintl phase thermoelectric material with the chemical formula Mg. 0.9 Zn 1.4 Yb 0.7 Sb2.
[0062] In this embodiment, the chemical formula is Mg 0.9 Zn 1.4 Yb 0.7 The preparation method of Sb2 p-type AB2X2 type Zintl phase thermoelectric material is as follows:
[0063] The elemental solid raw materials Mg, Zn, Yb, and Sb are arranged according to Mg 0.9 Zn 1.4 Yb 0.7 The Sb2 was weighed according to its stoichiometric ratio, and then the elemental solid and stainless steel balls were placed in a stainless steel ball mill jar in an argon atmosphere glove box with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0064] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0065] The Mg obtained in this embodiment 0.9 Zn 1.4 Yb 0.7 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0066] The Mg obtained in this embodiment 0.9 Zn 1.4 Yb 0.7 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-750K) are... zT Values such as Figure 3 As shown.
[0067] Example 6
[0068] This embodiment provides a p-type AB2X2 type Zintl phase thermoelectric material with the chemical formula Mg.0.6 Zn 1.6 Yb 0.8 Sb2.
[0069] In this embodiment, the chemical formula is Mg 0.6 Zn 1.6 Yb 0.8 The preparation method of Sb2 p-type AB2X2 type Zintl phase thermoelectric material is as follows:
[0070] The elemental solid raw materials Mg, Zn, Yb, and Sb are arranged according to Mg 0.6 Zn 1.6 Yb 0.8 The Sb2 was weighed according to its stoichiometric ratio, and then the elemental solid and stainless steel balls were placed in a stainless steel ball mill jar in an argon atmosphere glove box with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0071] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0072] The Mg obtained in this embodiment 0.6 Zn 1.6 Yb 0.8 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0073] The Mg obtained in this embodiment 0.6 Zn 1.6 Yb 0.8 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-750K) are... zT Values such as Figure 3 As shown.
[0074] Example 7
[0075] This embodiment provides a p-type AB2X2 type Zintl phase thermoelectric material with the chemical formula Mg. 1.2 Cd 1.2 Yb 0.6 Sb2.
[0076] In this embodiment, the chemical formula is Mg 1.2 Cd 1.2 Yb 0.6 The preparation method of Sb2 p-type AB2X2 type Zintl phase thermoelectric material is as follows:
[0077] The elemental solid raw materials Mg, Cd, Yb, and Sb are arranged according to Mg 1.2Cd 1.2 Yb 0.6 The Sb2 was weighed according to its stoichiometric ratio, and then the elemental solid and stainless steel balls were placed in a stainless steel ball mill jar in an argon atmosphere glove box with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0078] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0079] The Mg obtained in this embodiment 1.2 Cd 1.2 Yb 0.6 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0080] The Mg obtained in this embodiment 1.2 Cd 1.2 Yb 0.6 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-700K) are... zT Values such as Figure 4 As shown.
[0081] Example 8
[0082] This embodiment provides a p-type AB2X2 type Zintl phase thermoelectric material with the chemical formula Mg. 0.9 Cd 1.4 Yb 0.7 Sb2.
[0083] In this embodiment, the chemical formula is Mg 0.9 Cd 1.4 Yb 0.7 The preparation method of Sb2 p-type AB2X2 type Zintl phase thermoelectric material is as follows:
[0084] The elemental solid raw materials Mg, Cd, Yb, and Sb are arranged according to Mg 0.9 Cd 1.4 Yb 0.7 The Sb2 was weighed according to its stoichiometric ratio, and then the elemental solid and stainless steel balls were placed in a stainless steel ball mill jar in an argon atmosphere glove box with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0085] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0086] The Mg obtained in this embodiment 0.9 Cd 1.4 Yb 0.7 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0087] The Mg obtained in this embodiment 0.9 Cd 1.4 Yb 0.7 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-700K) are... zT Values such as Figure 4 As shown.
[0088] Example 9
[0089] This embodiment provides a p-type AB2X2 type Zintl phase thermoelectric material with the chemical formula Mg. 0.6 Cd 1.6 Yb 0.8 Sb2.
[0090] In this embodiment, the chemical formula is Mg 0.6 Cd 1.6 Yb 0.8 The preparation method of Sb2 p-type AB2X2 type Zintl phase thermoelectric material is as follows:
[0091] The elemental solid raw materials Mg, Cd, Yb, and Sb are arranged according to Mg 0.6 Cd 1.6 Yb 0.8 The Sb2 was weighed according to its stoichiometric ratio, and then the elemental solid and stainless steel balls were placed in a stainless steel ball mill jar in an argon atmosphere glove box with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0092] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0093] The Mg obtained in this embodiment 0.6 Cd 1.6 Yb 0.8 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0094] The Mg obtained in this embodiment0.6 Cd 1.6 Yb 0.8 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-700K) are... zT Values such as Figure 4 As shown.
[0095] Comparative Example 1
[0096] This comparative example provides a thermoelectric material with the chemical formula Mg3Sb2. The preparation method of the thermoelectric material with the chemical formula Mg3Sb2 in this comparative example is as follows:
[0097] The elemental solid raw materials Mg and Sb are weighed in a molar ratio of 3:2. Then, the powdered raw materials and stainless steel balls are loaded into a stainless steel ball mill jar in an argon atmosphere glove box, with a ball-to-material ratio of 10:1. The jar is then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0098] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0099] The XRD pattern of the Mg3Sb2 thermoelectric material obtained in this comparative example is as follows: Figure 1 As shown.
[0100] The electrical conductivity, Seebeck coefficient, and thermal conductivity of the Mg3Sb2 thermoelectric material obtained in this comparative example within the measured temperature range (300-750K) are... zT Values such as Figure 2 and Figure 3 As shown.
[0101] Comparative Example 2
[0102] This comparative example provides the chemical formula Mg. 1.8 Cd 0.8 Yb 0.4 Thermoelectric material of Sb2, in this comparative example, has the chemical formula Mg. 1.8 Cd 0.8 Yb 0.4 The preparation method of Sb2 thermoelectric materials is as follows:
[0103] The elemental solid raw materials Mg, Cd, Yb, and Sb are arranged according to Mg 1.8 Cd 0.8 Yb 0.4The Sb2 was weighed according to its stoichiometric ratio, and then the elemental solid and stainless steel balls were placed in a stainless steel ball mill jar in an argon atmosphere glove box with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0104] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0105] The Mg obtained in this embodiment 1.8 Cd 0.8 Yb 0.4 The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0106] The Mg obtained in this embodiment 1.8 Cd 0.8 Yb 0.4 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-700K) are... zT Values such as Figure 4 As shown.
[0107] Comparative Example 3
[0108] This comparative example provides the chemical formula Mg. 0.3 Cd 1.8 Yb 0.9 Thermoelectric material of Sb2, in this comparative example, has the chemical formula Mg. 0.3 Cd 1.8 Yb 0.9 The preparation method of Sb2 thermoelectric materials is as follows:
[0109] The elemental solid raw materials Mg, Cd, Yb, and Sb are arranged according to Mg 0.3 Cd 1.8 Yb 0.9 The Sb2 was weighed according to its stoichiometric ratio, and then the elemental solid and stainless steel balls were placed in a stainless steel ball mill jar in an argon atmosphere glove box with a ball-to-material ratio of 10:1. The jar was then subjected to high-energy ball milling at a speed of 1200 rpm for 10 hours.
[0110] The powder material obtained by high-energy ball milling was subjected to spark plasma sintering (SPS sintering) at a temperature of 600℃, a sintering pressure of 50MPa, and a sintering time of 5 minutes to finally obtain a dense thermoelectric material.
[0111] The Mg obtained in this embodiment 0.3 Cd 1.8 Yb 0.9The XRD pattern of Sb2 thermoelectric material is shown below. Figure 1 As shown.
[0112] The Mg obtained in this embodiment 0.3 Cd 1.8 Yb 0.9 The electrical conductivity, Seebeck coefficient, and thermal conductivity of Sb2 thermoelectric material within the measured temperature range (300-700K) are... zT Values such as Figure 4 As shown.
[0113] Experimental Example
[0114] The electrical conductivity and Seebeck coefficient of the thermoelectric materials provided in Examples 1-9 and Comparative Examples 1-3 were simultaneously measured using a commercially available ZEM-3 instrument from Ulvac, Japan. The conductivity was measured using the mature four-probe method. The sample size was approximately 3mm × 3mm × 9mm strips. A constant current was applied to ensure a uniform electric field distribution within the material. If the electric field strength was... E The current density flowing through the material is J Therefore, the expression for conductivity σ is: σ = In the formula, V The length of the sample along the current direction is l The potential difference between two points, I Cross-sectional area A The total current intensity passing through it. According to the definition of the Seebeck coefficient, the absolute Seebeck coefficient of the sample can be obtained by simply obtaining the temperature difference ΔT between two points in the material and the electrical current difference ΔV caused by this temperature difference.
[0115] The thermal conductivity of the thermoelectric materials provided in Examples 1-9 and Comparative Examples 1-3 is expressed by the formula... K = C p dλ Calculations show that, where C p is the specific heat capacity, estimated using the Duron-Petit law. d The density of the material is measured using Archimedes' principle; λ The thermal diffusivity was measured using a laser thermal conductivity meter (LFA-457). Before measurement, the sample was polished into a thin sheet approximately 6mm × 6mm × 1mm in size, and both sides were evenly and thinly sprayed with carbon powder before being placed in a lithium tantalate mold. Liquid nitrogen was added and the circulating water was turned on to prevent damage to the instrument due to heat. Protective gas was continuously introduced during the test. After the sample was heated to the set temperature, the system generated a laser and struck the sample. The sample gradually heated up under the laser's influence, and the temperature signal from its back side was received by a temperature detector. The thickness of the sample was measured before the experiment, and the results were combined with the instrument's recorded values.
[0116] Detected signal, through formula Calculate the thermal diffusivity.
[0117] Thermoelectric materials provided in Examples 1-9 and Comparative Examples 1-3 zT Value based on zT=S 2 σT / κ The formula calculates that, where S The Seebeck coefficient is... σ For electrical conductivity, κ Thermal conductivity, T This refers to absolute temperature.
[0118] Reference Figure 2 As shown, the Mg obtained in Examples 1-3 and Comparative Example 1 1.2 Zn 1.2 Ca 0.6 Sb2, Mg 0.9 Zn 1.4 Ca 0.7 Sb2, Mg 0.6 Zn 1.6 Ca 0.8 Thermoelectric performance measurements of Sb2 and Mg3Sb2 thermoelectric materials show that, within the measured temperature range (300-750K), the thermoelectric materials provided in Examples 1-3 exhibit high Seebeck coefficients and moderate electrical conductivity. Simultaneously, the thermoelectric materials provided in Examples 1-3 exhibit low thermal conductivity; within the temperature range of 300-750K, the thermal conductivity of the thermoelectric materials provided in Examples 1-3 is less than 1.15 W / m². -1 K -1 The Mg provided in Example 3 was calculated based on performance measurements. 0.6 Zn 1.6 Ca 0.8 Sb2 thermoelectric material zT The value can reach 0.81 at 750K, compared to Mg3Sb2 (provided in Comparative Example 1). zT The value was 0.26 at 750K, which is a 2.1-fold increase.
[0119] Reference Figure 3 As shown, the Mg obtained in Examples 4-6 and Comparative Example 1 1.2 Zn 1.2 Yb 0.6 Sb2, Mg 0.9 Zn 1.4 Yb 0.7 Sb2, Mg 0.6 Zn 1.6 Yb 0.8Thermoelectric performance measurements of Sb2 and Mg3Sb2 thermoelectric materials show that, within the measured temperature range (300-750K), the thermoelectric materials provided in Examples 4-6 possess moderate Seebeck coefficients and good electrical conductivity. Simultaneously, the thermoelectric materials provided in Examples 4-6 exhibit low thermal conductivity; within the temperature range of 300-750K, the thermal conductivity of the thermoelectric materials provided in Examples 4-6 is less than 1.07 W / m². -1 K -1 The Mg provided in Example 5 was calculated based on performance measurements. 0.9 Zn 1.4 Yb 0.7 Sb2 thermoelectric material zT The value can reach 1.06 at 750K, compared to Mg3Sb2 (provided in Comparative Example 1). zT The value was 0.26 at 750K, which is a 3-fold increase.
[0120] Reference Figure 4 As shown, the Mg obtained in Examples 7-9 and Comparative Examples 2-3 1.2 Cd 1.2 Yb 0.6 Sb2, Mg 0.9 Cd 1.4 Yb 0.7 Sb2, Mg 0.6 Cd 1.6 Yb 0.8 Sb2 and Mg 1.8 Cd 0.8 Yb 0.4 Sb2, Mg 0.3 Cd 1.8 Yb 0.9 Thermoelectric performance measurements of the Sb2 thermoelectric material show that, within the measured temperature range (300-700K), the thermoelectric materials provided in Examples 7-9 possess moderate Seebeck coefficients and good electrical conductivity. Simultaneously, the thermoelectric materials provided in Examples 7-9 exhibit low thermal conductivity; within the temperature range of 300-700K, the thermal conductivity of the thermoelectric materials provided in Examples 7-9 is less than 0.74 W / m². -1 K -1 The Mg provided in Example 9 was calculated based on performance measurements. 0.6 Cd 1.6 Yb 0.8 Sb2 thermoelectric material zT The value can reach 0.98 at 700K, compared to the Mg value provided in Comparative Example 2. 1.8 Cd 0.8 Yb 0.4 Sb2 ( zT The value (0.31 at 700K) is 2.1 times higher than that of Mg provided in Comparative Example 3. 0.3 Cd 1.8Yb 0.9 Sb2 ( zT (The value is 0.94 at 700K, indicating improved performance.)
[0121] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.
Claims
1. A type of p-type AB2X2 type Zintl phase thermoelectric material, characterized in that, The chemical formula of the p-type AB2X2 type Zintl phase thermoelectric material is Mg 3-3x Zn 2x Yb x Sb2 or Mg 3-3x Zn 2x Ca x Sb2 or Mg 3-3x Cd 2x Yb x Sb2, where x = 0.6~0.8; The preparation method of the p-type AB2X2-type Zintl phase thermoelectric material includes the following steps: Weigh out the elemental solids according to the stoichiometric ratio of the chemical formula of the p-type AB2X2 type Zintl phase thermoelectric material; The weighed elemental solid was placed into a ball milling apparatus under an inert atmosphere and subjected to high-energy ball milling. The powder after high-energy ball milling was sintered to obtain p-type AB2X2 type Zintl phase thermoelectric material; The sintering method is discharge plasma sintering, the mold for sintering is a graphite mold, the sintering temperature is 550~650℃, the sintering pressure is 50~60MPa, and the sintering time is 3~6 minutes.
2. The method for preparing the p-type AB2X2-type Zintl phase thermoelectric material according to claim 1, characterized in that, The elemental solid comprises at least one of the following: magnesium granules with a purity of 99.95 wt% to 99.999 wt%; antimony granules with a purity of 99.99 wt% to 99.999 wt%; zinc powder with a purity of 99.9 wt% to 99.99 wt%; ytterbium powder with a purity of 99.9 wt% to 99.99 wt%; cadmium powder with a purity of 99.9 wt% to 99.99 wt%; and calcium blocks with a purity of 99.9 wt% to 99.99 wt%.
3. The method for preparing the p-type AB2X2-type Zintl phase thermoelectric material according to claim 1, characterized in that, The inert atmosphere is an argon atmosphere.
4. The method for preparing the p-type AB2X2-type Zintl phase thermoelectric material according to claim 1, characterized in that, The ball-to-material ratio for the high-energy ball milling process is 5:1 to 10:1, the rotation speed is 1200 to 1500 revolutions per minute, and the processing time is 10 to 15 hours.
5. The application of the p-type AB2X2 type Zintl phase thermoelectric material according to claim 1 or the p-type AB2X2 type Zintl phase thermoelectric material prepared by the preparation method according to any one of claims 2-4 in thermoelectric devices.
6. The application according to claim 5, characterized in that, The thermoelectric device includes a thermoelectric power generation device or a thermoelectric refrigeration device in the medium-high temperature range.