JP2010027631A - Thermoelectric conversion element, thermoelectric conversion module, and method of manufacturing thermoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric conversion element capable of reducing contact resistance following junction between a p-type thermoelectric conversion material and an n-type thermoelectric conversion material, and to provide a thermoelectric conversion module and a method of manufacturing the thermoelectric conversion element. <P>SOLUTION: The thermoelectric conversion element 10 comprises a p-type thermoelectric conversion material 11 and an n-type thermoelectric conversion material 12. The p-type thermoelectric conversion material 11 has a layered perovskite structure represented by a compositional formula: A<SB>2</SB>BO<SB>4</SB>(wherein A and B represent one or more elements). The n-type thermoelectric conversion material 12 has a layered perovskite structure represented by a compositional formula: D<SB>2</SB>EO<SB>4</SB>(wherein D and E represent one or more elements). A part of the p-type thermoelectric conversion material 11 is bound to a part of the n-type thermoelectric conversion material 12 directly. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thermoelectric conversion element, a thermoelectric conversion module, and a method for manufacturing a thermoelectric conversion element. For example, the present invention relates to a thermoelectric conversion element capable of reducing contact resistance, a thermoelectric conversion module, and a method for manufacturing a thermoelectric conversion element.

  In recent years, environmental problems such as reduction of carbon dioxide have become important issues. In particular, thermoelectric conversion elements that can directly convert heat into electricity are expected to be put to practical use from the viewpoint of effective use of waste heat.

  As shown in FIG. 9, the conventional thermoelectric conversion element 100 includes two types of thermoelectric materials 101 and 102, a low temperature side electrode 106, and a high temperature side electrode 108. The two types of thermoelectric materials 101 and 102 are heat and electricity energy conversion materials. The thermoelectric materials 101 and 102 are respectively connected to the low temperature side electrode 106 at the low temperature side joint portion 103b which is the end surface on the low temperature side. Further, the thermoelectric materials 101 and 102 are connected via a high temperature side electrode 108 at a high temperature side joint portion 103a which is an end surface on the high temperature side. When the thermoelectric conversion element 100 is given a temperature difference between the high temperature side joint portion 103a and the low temperature side joint portion 103b, an electromotive force is generated due to the Seebeck effect, and electric power can be taken out.

Moreover, as the said thermoelectric materials 101 and 102, the oxide type thermoelectric conversion film of Unexamined-Japanese-Patent No. 2005-223307 (patent document 1) is mentioned, for example. The oxide-based thermoelectric conversion film disclosed in Patent Document 1 has RE _2-x M _x CuO _4-y (RE = La, Pr, Nd, Sm, Eu and a kind of rare earth element selected from Gd, M = At least one element selected from Ce, Ba, Sr and Ca, having a composition of 0 <X <2, 0 ≦ Y <4).

  Examples of the thermoelectric materials 101 and 102 include a thermoelectric conversion material disclosed in Japanese Patent Application Laid-Open No. 64-5911 (Patent Document 2). The thermoelectric conversion material disclosed in Patent Document 2 is characterized by comprising a rare earth element / transition element oxide having a perovskite structure.

Moreover, as the said thermoelectric conversion element 100, the thermoelectric power generation element of Unexamined-Japanese-Patent No. 8-306967 (patent document 3) is mentioned, for example. The thermoelectric power generation element disclosed in Patent Document 3 is characterized in that a part of two kinds of porous thermoelectric materials are directly bonded to each other via a bonding surface. It is disclosed that the two types of porous materials are made of alumel and chromel, for example. Since such a material has high thermal conductivity, it has been necessary to intentionally reduce the thermal conductivity as a porous material and to give a temperature difference to the thermoelectric conversion element.
JP 2005-223307 A JP-A 64-59911 JP-A-8-306967

  However, since the thermoelectric materials disclosed in Patent Documents 1 and 2 are made of a semiconductor material, the characteristics of the materials can be used effectively. However, the thermoelectric conversion element having the structure shown in FIG. There is a problem that the contact resistance with the thermoelectric material is high.

  Further, in the thermoelectric power generation element disclosed in Patent Document 3, two kinds of porous materials are used for the thermoelectric material. Therefore, there exists a problem that the contact resistance of the junction part of two types of thermoelectric materials is still high.

  Therefore, an object of the present invention is to solve the above-described problems, and a thermoelectric conversion element and a thermoelectric element that can reduce the contact resistance associated with the joining of the p-type thermoelectric conversion material and the n-type thermoelectric conversion material. It is providing the conversion module and the manufacturing method of a thermoelectric conversion element.

The thermoelectric conversion element of the present invention includes a p-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula A ₂ BO ₄ (A and B are one or more elements), a composition formula D ₂ EO ₄ (D And E is one or a plurality of elements) and an n-type thermoelectric conversion material having a layered perovskite structure. A part of the p-type thermoelectric conversion material and a part of the n-type thermoelectric conversion material are directly bonded.

  According to the thermoelectric conversion element of the present invention, the p-type thermoelectric conversion material and the n-type thermoelectric conversion material made of the material having the same crystal structure are directly joined, so that the p-type thermoelectric conversion material and the n-type thermoelectric conversion material Contact resistance can be reduced.

In the thermoelectric conversion element, preferably, A in the composition formula A ₂ BO ₄ and D in the composition formula D ₂ EO ₄ contain at least one rare earth element, and B in the composition formula A ₂ BO ₄ and the composition formula D ₂ EO E in ₄ contains at least one transition metal. Thereby, the contact resistance of the p-type thermoelectric conversion material and the n-type thermoelectric conversion material can be further reduced.

In the thermoelectric conversion element, preferably, A in the composition formula A ₂ BO ₄ includes lanthanum, and D in the composition formula D ₂ EO ₄ is at least one selected from the group consisting of praseodymium, neodymium, samarium, and gadolinium. It contains an element, and B in the composition formula A ₂ BO ₄ and E in the composition formula D ₂ EO ₄ contain copper. Thereby, the contact resistance between the p-type thermoelectric conversion material and the n-type thermoelectric conversion material can be further reduced.

  The thermoelectric conversion module of the present invention includes a plurality of the thermoelectric conversion elements. Since the thermoelectric conversion element that can reduce the contact resistance associated with the joining of the p-type thermoelectric conversion material and the n-type thermoelectric conversion material is provided, the thermoelectric conversion module also accompanies the joining of the p-type thermoelectric conversion material and the n-type thermoelectric conversion material. Contact resistance can be reduced.

The manufacturing method in one aspect of the thermoelectric conversion element of the present invention is a method of using a raw material of a p-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula A ₂ BO ₄ (A and B are one or more elements). A step of preparing, a step of preparing a raw material of an n-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula D ₂ EO ₄ (D and E are one or more elements), and a p-type thermoelectric conversion material And a step of directly bonding the p-type thermoelectric conversion material and the n-type thermoelectric conversion material.

  According to the method for manufacturing a thermoelectric conversion element in one aspect of the present invention, a p-type thermoelectric conversion material and an n-type thermoelectric conversion material made of a material having the same crystal structure can be directly joined. Therefore, a thermoelectric conversion element that can reduce the contact resistance between the p-type thermoelectric conversion material and the n-type thermoelectric conversion material can be manufactured.

According to another aspect of the present invention, there is provided a method for producing a thermoelectric conversion element comprising a raw material of a p-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula A ₂ BO ₄ (where A and B are one or more elements). Preparing and forming a sheet, and preparing a raw material of an n-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula D ₂ EO ₄ (where D and E are one or more elements), and a sheet Forming a laminate, obtaining a laminate by laminating a sheet of p-type thermoelectric conversion material and a sheet of n-type thermoelectric conversion material, co-sintering the laminate, and making cuts in the joints And a step of directly joining the p-type thermoelectric conversion material and the n-type thermoelectric conversion material.

  According to the method for manufacturing a thermoelectric conversion element in another aspect of the present invention, a p-type thermoelectric conversion material and an n-type thermoelectric conversion material made of a material having the same crystal structure can be directly joined. Therefore, a thermoelectric conversion element that can reduce the contact resistance between the p-type thermoelectric conversion material and the n-type thermoelectric conversion material can be manufactured. Moreover, thickness design becomes easy, such as enlarging the thickness of the sheet | seat of material with high resistance among the sheet | seat of p-type thermoelectric conversion material, and the sheet | seat of n-type thermoelectric conversion material.

  According to the thermoelectric conversion element, the thermoelectric conversion module, and the thermoelectric conversion element manufacturing method of the present invention, the p-type thermoelectric conversion material and the n-type thermoelectric conversion material made of the same crystal structure material are directly bonded. The contact resistance accompanying the joining of the type thermoelectric conversion material and the n-type thermoelectric conversion material can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing a thermoelectric conversion element according to Embodiment 1 of the present invention. With reference to FIG. 1, the thermoelectric conversion element in Embodiment 1 of this invention is demonstrated. As shown in FIG. 1, the thermoelectric conversion element 10 in Embodiment 1 includes a p-type thermoelectric conversion material 11 and an n-type thermoelectric conversion material 12. The p-type thermoelectric conversion material 11 has a layered perovskite structure represented by a composition formula A ₂ BO ₄ (A and B are one or more elements). The n-type thermoelectric conversion material 12 has a layered perovskite structure represented by a composition formula D ₂ EO ₄ (D and E are one or more elements). A part of the p-type thermoelectric conversion material 11 and a part of the n-type thermoelectric conversion material 12 are directly joined. Note that “direct bonding” means that the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 are directly bonded so as not to have an electrode interposed therebetween.

  Specifically, the thermoelectric conversion element 10 includes one p-type thermoelectric conversion material 11, one n-type thermoelectric conversion material 12, and two electrodes 16. The p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 are directly bonded to each other at the high-temperature side bonding portion 13a. In the first embodiment, in FIG. 1, the high-temperature side joint 13a is the high temperature side, and the joint connected to the electrode is the low temperature side.

  The thermoelectric conversion elements 10 are separated from each other in a portion other than the portion where the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 are joined (in the first embodiment, a portion other than the high-temperature side joint portion 13a). It faces through the separation part 17 which is.

  In addition, an insulating ceramic thin plate or a glass material may be inserted into the separating portion 17 in order to ensure reinforcement and insulation.

The p-type thermoelectric conversion material 11 has a layered perovskite structure represented by a composition formula A ₂ BO ₄ (A and B are one or more elements). A in the composition formula A ₂ BO ₄ preferably contains at least one rare earth element, and particularly preferably contains lanthanum (La). Further, B in the composition formula A ₂ BO ₄ preferably contains at least one transition metal. Moreover, it is especially preferable that copper is included as one kind of transition metal.

The n-type thermoelectric conversion material 12 has a layered perovskite structure represented by a composition formula D ₂ EO ₄ (D and E are one or more elements). D in the composition formula D ₂ EO ₄ preferably contains at least one rare earth element, and is selected from the group consisting of praseodymium (Pr), neodymium (Nd), samarium (Sm), and gadolinium (Gd). It is particularly preferred that it contains at least one element. Further, E in the composition formula D ₂ EO ₄ preferably contains at least one transition metal. Moreover, it is especially preferable that copper is included as one kind of transition metal.

In the composition formula A ₂ BO ₄ and the composition formula D ₂ EO ₄ , A, B, D and E are represented by one or a plurality of elements, and when composed of a plurality of elements, the composition formula A ₂ means that the sum of the atomic ratios of A and D in BO ₄ and composition formula D ₂ EO ₄ is 2. Moreover, it means that the sum of the atomic ratios of B and E in composition formula A ₂ BO ₄ and composition formula D ₂ EO ₄ is 1. O means oxygen.

  The p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 have a layered perovskite structure and have the same crystal structure.

  The electrode 16 is a terminal electrode. Therefore, the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 disposed at the end of the thermoelectric conversion element 10 are connected to the low-temperature end. In the first embodiment, the electrode 16 is connected to the end portion on the low temperature side, but is not particularly limited thereto, and may be connected to the high temperature side, or connected to the low temperature side and the high temperature side. It may be.

Next, the manufacturing method of the thermoelectric conversion element 10 in embodiment is demonstrated. First, a raw material of a p-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula A ₂ BO ₄ (A and B are one or more elements), and a composition formula D ₂ EO ₄ (D and E are 1). A step of preparing a raw material of an n-type thermoelectric conversion material having a layered perovskite structure represented by (single or plural elements) is performed. The preparing step preferably includes at least one rare earth element and at least one transition metal, and includes at least one selected from the group consisting of La, Pr, Nd, Sm, Gd, and Cu. More preferably, it contains an element.

Specifically, A in the composition formula A ₂ BO ₄ contains at least one rare earth element, B contains the p-type thermoelectric conversion material 11 containing at least one transition metal, and D in the composition formula D ₂ EO ₄ is at least In order to produce the n-type thermoelectric conversion material 12 containing one kind of rare earth element and E containing at least one kind of transition metal, a starting material is prepared. For example, a starting material containing a rare earth element such as La, Pr, Nd, Sm, and Gd and a transition element such as Cu is prepared. Of these starting materials, for Pr, Cu, Ni and Fe, for example, oxides are used, and for Ca, Sr, Ba and Mn, for example, carbonates are preferably used. These starting materials are appropriately selected depending on conditions necessary for thermoelectric characteristics, power generation characteristics, and co-sintering. Moreover, you may add another element as needed for the co-sintering mentioned later.

  In addition, it will not specifically limit if a metal oxide can be formed by baking, For example, other inorganic compounds, such as a hydroxide, and organometallic compounds, such as an alkoxide, may be used. Further, the powder used as a starting material is not particularly limited in particle size and the like, but preferably has a particle size that can be uniformly mixed.

  The above starting materials are weighed so as to give a desired composition ratio, and then pulverized and mixed. For this pulverization and mixing treatment, for example, a wet ball mill using a dispersion medium as water is used. In addition, the time which performs a ball mill is not specifically limited, It is preferable to set it as the time mixed uniformly. Thereby, the mixed powder of a starting material is obtained. When water is used as a dispersion medium, an operation for evaporating water is then performed.

  Then, the mixed powder of the starting material is calcined, for example, in the atmosphere. When calcination, the temperature is preferably set to 800 ° C to 1100 ° C. By setting this temperature range, the reaction is promoted. Thereby, the target p-type thermoelectric conversion material powder and n-type thermoelectric conversion material powder are obtained. In addition, when the above-mentioned calcination is finished, an unreacted part may remain in the powder.

  Then, the p-type thermoelectric conversion material powder and the n-type thermoelectric conversion material powder are pulverized by a ball mill or the like as described above, and pure water and a binder are added to form a slurry. The obtained slurry is formed into a sheet by, for example, a doctor blade method. Thereby, a sheet-like p-type thermoelectric conversion material and n-type thermoelectric conversion material are obtained.

  In addition, the particle size of the powder obtained when pulverizing after calcination is not particularly limited, but the smaller the particle size is preferable from the viewpoint of reducing the thermal conductivity.

  Next, the raw material of the p-type thermoelectric conversion material 11 and the raw material of the n-type thermoelectric conversion material 12 are co-sintered, and the step of directly joining the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 is performed. . Thereby, the thermoelectric conversion element 10 in Embodiment 1 of this invention shown in FIG. 1 is obtained.

  Specifically, the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 are adjusted so that the obtained sheet-like p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 have a predetermined thickness. Are laminated to form a laminate.

  And the obtained laminated body is crimped | bonded by the isotropic isostatic pressing method etc., for example, and a molded object is manufactured. The obtained molded body is degreased at, for example, 300 ° C. to 600 ° C., and then fired, for example, in the atmosphere. At this time, it is preferable to fire in a temperature range in which the relative density is 90% or more. By setting this temperature, the sintering easily proceeds. In addition, the method of baking is not specifically limited, It can carry out by a generally well-known method. Thereby, the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 can be directly joined.

  And about the obtained element, parts other than the high temperature side junction part 13a are cut | disconnected, and the isolation | separation part 17 is formed. Furthermore, if necessary, the thermoelectric conversion element 10 shown in FIG. 1 can be formed by forming it into a predetermined shape.

  Note that, as described above, in Embodiment 1, the laminated body is co-sintered, and then the portions other than the high-temperature side joint portion 13a are cut, but the present invention is not particularly limited thereto. After cutting the laminated body (forming the separation part 17), the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 may be directly joined by co-sintering.

  The method for providing the temperature difference between the high temperature portion and the low temperature portion of the thermoelectric conversion element 10 shown in FIG. 1 manufactured in this way is not particularly limited, but waste heat may be used or a heating member (not shown). Or a cooling member (not shown) may be used.

As described above, according to the thermoelectric conversion element 10 in Embodiment 1 of the present invention, p having a layered perovskite structure represented by the composition formula A ₂ BO ₄ (A and B are one or a plurality of elements). P-type thermoelectric conversion material 11, and n-type thermoelectric conversion material 12 having a layered perovskite structure represented by a composition formula D ₂ EO ₄ (where D and E are one or more elements). And a part of the n-type thermoelectric conversion material 12 are directly bonded. In the conventional thermoelectric conversion element 100 shown in FIG. 9, contact resistance is generated for the following reason. When the thermoelectric materials 101 and 102 are made of a semiconductor, the Fermi level of the semiconductor and the Fermi level of the metal are different (the Fermi level of the n-type semiconductor> the Fermi level of the metal. The Fermi level of the p-type semiconductor <the metal's Fermi level. Fermi level). When a metal and a semiconductor come into contact, a depletion layer is generated near the semiconductor junction surface to form a barrier, so that the Fermi levels of the metal and the semiconductor match (the height of the barrier of the n-type semiconductor is the work of the metal). Depends on the function and the electron affinity of the n-type semiconductor, and the barrier height of the p-type semiconductor depends on the electron affinity of the p-type semiconductor, the energy gap of the p-type semiconductor, and the work function of the metal. When the Fermi level is almost the same as that of the semiconductor, no barrier is formed, but the position of the Fermi level differs depending on the polarity of the semiconductor. The Fermi level of the n-type semiconductor is a position close to the conduction band, and the Fermi level of the p-type semiconductor is a position close to the valence band. Therefore, a metal that does not form a barrier with respect to a p-type semiconductor forms a barrier with respect to an n-type semiconductor, and the reverse relationship also holds. A thermoelectric conversion element that uses a semiconductor as a thermoelectric material always uses a bipolar polarity of a p-type semiconductor and an n-type semiconductor, and therefore a contact resistance between the electrode and the thermoelectric material is generated with either polarity. However, in the thermoelectric conversion element 10 according to Embodiment 1 of the present invention, the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 made of the material having the same crystal structure are directly joined. It is not necessary to provide an electrode between 11 and the n-type thermoelectric conversion material 12. Therefore, it is possible to eliminate the contact resistance generated at the junction between the electrode and the p-type thermoelectric conversion material and the n-type thermoelectric conversion material.

  Further, since the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 are made of the same crystal structure, the contact resistance of the high-temperature side joint portion 13a can be further reduced. In the case of dissimilar materials, co-sintering is difficult unless a special firing such as hot pressing, high temperature isostatic pressing, or discharge plasma sintering is used.

  Furthermore, since it is not necessary to provide an electrode between the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12, oxidation due to metal occurs at the high-temperature side joining portion 13a and does not deteriorate. Therefore, the high temperature side of the thermoelectric conversion element 10 can be made higher. Furthermore, since the gap between the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 can be narrowed, the density can be increased. Furthermore, the size can be reduced.

In the thermoelectric conversion element 10, preferably, A in the composition formula A ₂ BO ₄ and D in the composition formula D ₂ EO ₄ include at least one rare earth element, and B and the composition formula D ₂ in the composition formula A ₂ BO ₄ . E in EO ₄ contains at least one transition metal. Thereby, the contact resistance of the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 can be further reduced.

Preferably, in the above thermoelectric conversion element 10, the A in the formula A ₂ BO _4, wherein the lanthanum, D in formula D ₂ EO ₄ is praseodymium, neodymium, samarium, and at least one selected from the group consisting of gadolinium And B in the composition formula A ₂ BO ₄ and E in the composition formula D ₂ EO ₄ contain copper. Thereby, the contact resistance between the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 can be further reduced.

Method for manufacturing a thermoelectric conversion element 10 in the first embodiment of the present invention, the composition formula A ₂ BO ₄ p-type thermoelectric conversion material 11 (A and B of one or more elements) having a layered perovskite structure represented by A step of preparing a raw material of n-type thermoelectric conversion material 12 having a layered perovskite structure represented by a composition formula D ₂ EO ₄ (where D and E are one or more elements), p A step of co-sintering a raw material of the n-type thermoelectric conversion material 11 and a raw material of the n-type thermoelectric conversion material 12 and directly bonding the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12. According to the manufacturing method of the thermoelectric conversion element 10 of the present invention, the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 made of the same crystal structure material can be directly joined. Therefore, the thermoelectric conversion element 10 that can reduce the contact resistance between the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 can be manufactured.

  Moreover, since the material of the same crystal structure is selected for the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 in the preparation step, they can be co-sintered without using a special firing method. Therefore, the thermoelectric conversion element 10 can be manufactured easily.

  In addition, since it is not necessary to form an electrode for bonding between the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12, a process for producing an electrode is not necessary when the thermoelectric conversion element 10 is manufactured. Become. Moreover, since it joins when co-sintering the raw material of the p-type thermoelectric conversion material 11 and the raw material of the n-type thermoelectric conversion material 12, the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 are joined. Therefore, only the process is not required. Therefore, since the number of steps for manufacturing the thermoelectric conversion element 10 can be reduced, the cost can be reduced and the manufacturing can be simplified.

  Further, when the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 include a carrier element, the carrier element diffuses in the high-temperature side joint portion 13a as compared with the thermoelectric conversion element including an electrode. Since it is difficult, loss of carrier elements can be reduced.

The manufacturing method of the thermoelectric conversion element in the embodiment of the present invention is the raw material of the p-type thermoelectric conversion material 11 having a layered perovskite structure represented by the composition formula A ₂ BO ₄ (A and B are one or a plurality of elements). And a raw material for the n-type thermoelectric conversion material 12 having a layered perovskite structure represented by a composition formula D ₂ EO ₄ (where D and E are one or more elements) A step of forming a sheet, a step of laminating a sheet of p-type thermoelectric conversion material 11 and a sheet of n-type thermoelectric conversion material 12 to obtain a laminate, and co-sintering the laminate, And a step of directly joining the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 by making a cut (forming the separation portion 17). Thereby, thickness design becomes easy, such as enlarging the thickness of the sheet | seat of a material with high resistance among the sheet | seat of the p-type thermoelectric conversion material 11, and the sheet | seat of the n-type thermoelectric conversion material 12. Therefore, the thermoelectric conversion element 10 can be manufactured more easily.

(Embodiment 2)
FIG. 2 is a schematic cross-sectional view showing a thermoelectric conversion module according to Embodiment 2 of the present invention. With reference to FIG. 2, the thermoelectric conversion module in Embodiment 2 of this invention is demonstrated. The thermoelectric conversion module 30 in the second embodiment includes a plurality of thermoelectric conversion elements 10 in the first embodiment.

  Specifically, the thermoelectric conversion module 30 includes two thermoelectric conversion elements 10 each having one p-type thermoelectric conversion material 11 and one n-type thermoelectric conversion material 12 and two electrodes 16. In each thermoelectric conversion element 10 constituting the thermoelectric conversion module 30, the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 are directly bonded to each other at the high-temperature side bonding portion 13a. Then, the p-type thermoelectric conversion material 11 of one thermoelectric conversion element 10 and the n-type thermoelectric conversion material 12 of the other thermoelectric conversion element 10 are directly bonded to each other at a low-temperature side bonding portion 13b. In the second embodiment, in FIG. 2, the high-temperature side joint 13 a is the high temperature side, and the low-temperature side joint 13 b is the low temperature side.

  Further, the thermoelectric conversion element 10 constituting the thermoelectric conversion module 30 is a portion other than the portion where the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 are bonded (in the second embodiment, the high-temperature side bonding). In the portion other than the portion 13a and the low-temperature side joint portion 13b), they face each other through the separation portion 17 that is separated from each other.

  The method for manufacturing the thermoelectric conversion module 30 in the second embodiment is manufactured by manufacturing a plurality of thermoelectric conversion elements 10 in the first embodiment. Specifically, a plurality of elements can be obtained by directly joining a plurality (two in the second embodiment) of the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12.

  And about the obtained some element, parts other than the high temperature side junction part 13a and the low temperature side junction part 13b are cut | disconnected, and the isolation | separation part 17 is formed. Furthermore, the thermoelectric conversion module 30 shown in FIG. 2 can be formed by forming in a predetermined shape as needed.

  In addition, although the thermoelectric conversion module 30 in Embodiment 2 was set as the structure provided with the two thermoelectric conversion elements 10, if it is provided with the two or more thermoelectric conversion elements 10, it will not specifically limit to this.

  As described above, according to the thermoelectric conversion module 30 in the second embodiment of the present invention, a plurality of the thermoelectric conversion elements 10 in the first embodiment are provided. Thereby, the thermoelectric conversion module 30 can reduce the contact resistance accompanying joining of a p-type thermoelectric conversion material and an n-type thermoelectric conversion material. Moreover, since the thermoelectric conversion element 10 is provided with two or more, conversion efficiency can be improved. Furthermore, since it is not necessary to form an electrode between the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12, the gap can be narrowed, so that the size can be reduced.

[Example]
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

(Examples 1-3)
The thermoelectric conversion elements in Examples 1 to 3 were manufactured according to the method for manufacturing a thermoelectric conversion element in Embodiment 1. Specifically, first, La ₂ O ₃ , Sr ₂ CO ₃ and CuO were prepared as raw material powders for the p-type thermoelectric conversion material. Further, Pr ₆ O ₁₁ , CeO ₂ and CuO were prepared as raw material powders for the n-type thermoelectric conversion material. These raw material powders were weighed so as to have the composition described in Table 1 below.

  Next, the weighed raw material powder was pulverized and mixed in a ball mill for 16 hours using pure water as a solvent. Pure water and a binder were added to the pulverized raw material powder and mixed, and the resulting slurry was formed into a sheet by a doctor blade method. The obtained sheet was baked and adjusted to have a thickness of 1.5 mm to prepare a p-type sheet and an n-type sheet. And the n-type sheet | seat was laminated | stacked on the p-type sheet | seat, and the laminated body was obtained.

  Next, the laminate was pressure-bonded at 200 MPa by an isotropic isostatic pressing method to obtain a molded body. The obtained molded body was degreased at 480 ° C. and then fired at 1025 ° C. in an air atmosphere. When the sample obtained by sintering was observed by X-ray diffraction (XRD), as shown in FIG. 3, each layer having a layered perovskite structure had a peculiar peak. It was confirmed that it had. In addition, FIG. 3 is a figure which shows the XRD chart in an Example.

  As shown in FIG. 4, the obtained sample was 3 mm (D) (D1 of the p-type thermoelectric conversion material 11 was 1.5 mm, D2 of the n-type thermoelectric conversion material 12 was 1.5 mm) × 4 mm (L) × 6 mm Cut to (H1), and cut a 0.2 mm (K) width so that the junction (high temperature side junction 13a) of the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 remains 1.5mm (H2). I put it in. This obtained the thermoelectric conversion element in Examples 1-3 shown in FIG. FIG. 4 is a schematic perspective view showing thermoelectric conversion elements of Examples 1 to 3 of the present invention.

(Comparative Examples 1-8)
Although the thermoelectric conversion elements of Comparative Examples 1 to 8 were basically manufactured in the same manner as the thermoelectric conversion elements of Examples 1 to 3, the p-type thermoelectric conversion material and the n-type thermoelectric conversion material were the electrodes shown in Table 2. It differs from the thermoelectric conversion element of Examples 1-3 only in the joined point.

  Specifically, the same raw material powder as in Examples 1 to 3 was prepared, and these raw material powders were weighed so as to have the composition described in Table 1 below. Next, the weighed raw material powder was pulverized and mixed in a ball mill for 16 hours using pure water as a solvent. The obtained slurry was dried and then calcined at 900 ° C. in an air atmosphere.

Next, a binder was added to the obtained mixed powder, and pulverization and mixing were performed with a ball mill for 16 hours using pure water as a solvent. And the obtained slurry was dried, and it shape | molded by 1000 kg / cm < ² > after that using the press, and the molded object was obtained. The obtained molded body was degreased at 400 ° C., and then fired at 1025 ° C. in an air atmosphere.

  Next, each of the obtained samples was cut into 1.5 mm × 4 mm × 5 mm, and p-type thermoelectric conversion material and n-type thermoelectric conversion material were compared. Comparative Examples 1 to 4 were Cu electrodes, and Comparative Examples 5 to 8 were used. Were joined by Ag electrodes. Thereby, the thermoelectric conversion element in Comparative Examples 1-8 was obtained.

(Evaluation methods)
As shown in FIG. 5, in the thermoelectric conversion elements in Examples 1 to 3, a junction obtained by directly joining the p-type thermoelectric conversion material 11 and the n-type thermoelectric conversion material 12 is referred to as a high-temperature side junction 13a, and the high-temperature side junction 13a. The terminal electrode 16 made of Ag was connected with the end surface opposite to the low temperature side. In the thermoelectric conversion elements in Comparative Examples 1 to 8, the joint part joined with the Cu electrode or the Ag electrode is the high temperature side joint part, and the end surface opposite to the high temperature side joint part is the low temperature side, and for the same terminal as in Examples 1 to 3 The electrode 16 was connected. FIG. 5 is a schematic cross-sectional view showing a method for measuring thermoelectric conversion elements in Examples 1 to 3 of the present invention.

  And the junction part of the high temperature side was heated with the heating member. Moreover, the junction part of the low temperature side was fixed to 20 degreeC using the water cooling plate. The heating member was heated to 50 ° C., 100 ° C., 150 ° C., 200 ° C., 250 ° C., 300 ° C., 350 ° C., and 400 ° C. so that the temperature of the high-temperature side junction was higher than that of the low-temperature side junction. . A resistance heating type cartridge heater was used as the heating member. And the electromotive force and electric current which generate | occur | produce in the thermoelectric conversion element in Examples 1-3 and Comparative Examples 1-8 were measured in this case, and the output was computed. The results are shown in FIGS. However, as shown in FIGS. 6-8, since there is a difference in thermal conductivity depending on the material composition, the measured temperature of the thermoelectric conversion module is different. In addition, FIG. 6 is a figure which shows the relationship between the electromotive force and temperature difference of the thermoelectric conversion element in Examples 1-3. FIG. 7 is a diagram illustrating the relationship between the current of the thermoelectric conversion element and the temperature difference in Examples 1 to 3. FIG. 8 is a diagram illustrating the relationship between the output of the thermoelectric conversion element and the temperature difference in Examples 1 to 3.

  Moreover, about the thermoelectric conversion element in Examples 1-3 and Comparative Examples 1-8, element resistance R13a ((omega | ohm)) of the high temperature side junction part 13a part was measured as follows. Hereinafter, R16 is the resistance of the electrode 16, R11 is the resistance of the p-type thermoelectric conversion material 11, R13a is the resistance of the high-temperature side joint 13a, and R12 is the resistance of the n-type thermoelectric conversion material 12. First, R11 and R12 were measured by the four probe method, and samples (R16 + R11 + R16) and (R16 + R12 + R16) were prepared and their resistances were measured. From this, the resistances of (R11 + R16) and (R12 + R16) were determined. And (R16 + R11 + R13a + R12 + R16) was measured. Finally, by calculating (R16 + R11 + R13a + R12 + R16) − (R11 + R16) − (R12 + R16), the element resistance R13a of the high temperature side junction 13a portion was obtained. The results are shown in Table 2.

(Measurement result)
As shown in Table 2, it was confirmed that the thermoelectric conversion elements of Examples 1 to 3 can reduce the element resistance as compared with the thermoelectric conversion elements of Comparative Examples 1 to 8.

  Moreover, as shown in FIGS. 6-8, it has confirmed that the thermoelectric element of Examples 1-3 was so high that an electromotive force, an electric current, and an output were so high that a temperature difference was high. From this result, since the thermoelectric conversion element of Examples 1-3 was not provided with the electrode, it has confirmed that even if the high temperature side of the thermoelectric conversion element was heated to high temperature, a problem did not arise. In addition, it was found that only Pr and La were diffused in the junction, and Ce and Sr, which are carrier addition elements, were not diffused, and the carrier loss was small.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims for patent, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims for patent.

It is a schematic sectional drawing which shows the thermoelectric conversion element in Embodiment 1 of this invention. It is a schematic sectional drawing which shows the thermoelectric conversion module in Embodiment 2 of this invention. It is a figure which shows the XRD chart in an Example. It is a schematic perspective view which shows the thermoelectric conversion element of Examples 1-3 of this invention. It is a schematic sectional drawing which shows the method of measuring the thermoelectric conversion element in Examples 1-3 of this invention. It is a figure which shows the relationship between the electromotive force of the thermoelectric conversion element in Examples 1-3, and a temperature difference. It is a figure which shows the relationship between the electric current of the thermoelectric conversion element in Examples 1-3, and a temperature difference. It is a figure which shows the relationship between the output of the thermoelectric conversion element in Examples 1-3, and a temperature difference. It is a schematic sectional drawing which shows the conventional thermoelectric conversion element.

Explanation of symbols

  10, 100 thermoelectric conversion element, 11 p-type thermoelectric conversion material, 12 n-type thermoelectric conversion material, 13a, 103a high-temperature side junction, 13b, 103b low-temperature side junction, 16 electrodes, 17 separation unit, 30 thermoelectric conversion module, 31 Heating member, 101, 102 thermoelectric material, 106 low temperature side electrode, 108 high temperature side electrode.

Claims (6)

A p-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula A ₂ BO ₄ (where A and B are one or more elements);
An n-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula D ₂ EO ₄ (D and E are one or more elements),
A part of the p-type thermoelectric conversion material and a part of the n-type thermoelectric conversion material are directly joined to each other. A in the composition formula A ₂ BO ₄ and D in the composition formula D ₂ EO ₄ contain at least one rare earth element,
_{2. The} thermoelectric conversion element according to claim 1, wherein B in the composition formula A ₂ BO ₄ and E in the composition formula D ₂ EO ₄ include at least one transition metal. A in the composition formula A ₂ BO ₄ includes lanthanum,
D in the composition formula D ₂ EO ₄ includes at least one element selected from the group consisting of praseodymium, neodymium, samarium, and gadolinium;
The thermoelectric conversion element according to claim 1, wherein B in the composition formula A ₂ BO ₄ and E in the composition formula D ₂ EO ₄ include copper.   The thermoelectric conversion module provided with two or more thermoelectric conversion elements of any one of Claims 1-3. Preparing a raw material of a p-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula A ₂ BO ₄ (A and B are one or more elements);
Preparing a raw material of an n-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula D ₂ EO ₄ (D and E are one or more elements);
Thermoelectric conversion comprising co-sintering the raw material of the p-type thermoelectric conversion material and the raw material of the n-type thermoelectric conversion material and directly joining the p-type thermoelectric conversion material and the n-type thermoelectric conversion material. Device manufacturing method. Preparing a raw material of a p-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula A ₂ BO ₄ (where A and B are one or more elements), and forming the sheet into a sheet;
Preparing a raw material of an n-type thermoelectric conversion material having a layered perovskite structure represented by a composition formula D ₂ EO ₄ (where D and E are one or more elements), and molding the raw material into a sheet;
Laminating the sheet of the p-type thermoelectric conversion material and the sheet of the n-type thermoelectric conversion material to obtain a laminate;
A method for manufacturing a thermoelectric conversion element, comprising: co-sintering the laminate, cutting a joint, and directly joining the p-type thermoelectric conversion material and the n-type thermoelectric conversion material.

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