JP2001217469A - Thermoelectric conversion element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric conversion element that is in a configuration where the thermoelectric conversion efficiency of an Si-group material that is an inexpensive and light thermoelectric conversion material has been improved extremely and at the same time uses and Si group that is in a configuration for facilitating manufacturing, and its manufacturing method. SOLUTION: When the thermoelectric conversion element is subjected to compression molding in p/n/p/n/p/ configuration for integration sintering by alternately arranging n-type and p-type material power and including an insulation material such as Si-system and ceramic power outside the scheduled part of pn junction, integration can be facilitated extremely, and at the same time loss due to electrode junction can be reduced to almost zero. At the same time, joining is made to a pn junction that is located at high-temperature and low- temperature sides for forming an element via a hetero metal when a temperature gradient is given to the thermoelectric conversion element, thus improving electromotive force and the amount of electricity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easy-to-manufacture thermoelectric conversion element using a Si-based thermoelectric conversion material or the like, in which n-type and p-type semiconductors are alternately arranged, each having an electrode material and an insulating material interposed therebetween. The present invention relates to a thermoelectric conversion element capable of extracting energies with high efficiency by significantly increasing the thermoelectric conversion efficiency of a Si-based material by performing pn junction by integral molding and a method of manufacturing the same.

[0002]

2. Description of the Related Art Thermoelectric conversion elements have attracted attention in recent years in view of energy and environmental issues such as CO ₂ reduction, and are expected to be put to practical use from the viewpoint of effective use of thermal energy. is there.

[0003] For example, a system that converts waste heat from incinerators and power plant turbines into electric energy, a portable power generator for easily obtaining electricity outdoors or in space, a flame sensor for gas appliances, A very wide range of uses are being studied, such as using the battery together with a fuel cell or using waste heat of an internal combustion engine of an automobile to improve fuel efficiency.

[0004] However, the thermoelectric conversion elements known so far generally have a low conversion efficiency, a very narrow operating temperature range, a problem of environmental pollution of the elements used, and high raw material and production costs. Has not become widely used.

[0005] The conversion efficiency from heat energy to electric energy is a function of the figure of merit ZT, and increases as ZT increases. This figure of merit ZT is expressed as ZT = S ² σT / κ formula. Where S is the Seebeck coefficient of the thermoelectric material, σ
Is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature expressed as the average value of the high temperature side (T _H ) and the low temperature side (T _L ) of the thermoelectric element.

At present, the thermoelectric material having the highest figure of merit is IrSb ₃ having a skutterudite type crystal structure (T. Calllet, A. Borsh
chrysky and J.-P.Fleurial: Proc. 12th Int. Con
f. on Thermoelectrics, (Yokohama, Japan, 1993) P13
2.) and its ZT value is about 2.0. However, Ir
Due to the high raw material cost, it has not been put to practical use.

Further, Bi ₂ Te _3, which exhibits a high figure of merit at a low temperature, is used as a Peltier element as a cooling element such as a semiconductor, but has a problem that the operating temperature range is narrow due to its low melting point of 530 K. .

[0008] On the other hand, Fe-Si based materials are considered promising in terms of cost and environment, but this system has a figure of merit (ZT).
The value was 0.2 or less, which was far below the characteristics required as a thermoelectric conversion material.

[0009] Si-Ge based materials are described in B. Abeles (Phys. Rev. 131,
1906, (1963)) investigated the composition dependence of thermal conductivity of Si-Ge alloys and reported that the thermal conductivity could be greatly reduced by alloying Si and Ge. In their report, it was reported that thermal conductivity did not decrease unless the Ge content was 20-30 atomic%.

[0010] However, the high raw material cost of Ge
And Ge have a wide range of liquidus and solidus lines,
There is a problem that it is difficult to produce a uniform composition by dissolution or zone leveling. Further, a hot press method has been attempted to make the composition uniform, but the mass productivity is poor.

[0011] Further, JP-A-11-54808 discloses that disc-shaped n-type and p-type preforms are prepared by using Si-Ge alloy powder, and n, p, n, and p are formed in this order. The four preforms are laminated and sintered, then processed into a rectangular parallelepiped, and then cut to form a separation between n and p, producing a thermoelectric conversion element with a shape like a fold A way to do that has been proposed. However, not only is the manufacturing process complicated and labor is required for processing, but also the properties of the material itself are inferior.

[0012]

SUMMARY OF THE INVENTION The present inventors have paid attention to the fact that Si, which is widely used as a semiconductor device, has an extremely high Seebeck coefficient. It has been found that addition of a small amount of an element of 0.001 to 20 atomic% can result in a thermoelectric conversion material having a high figure of merit (WO99 / 22410).

[0013] Si is characterized in that it has a small environmental load, has abundant resources, has relatively low material costs, and is light. In addition, the inventors have found that the Seebeck coefficient can be increased by selecting the electrode at the joint, and that the electric power that can be extracted is improved.

[0014] However, when the thermoelectric conversion material is used as an element, if the junction between the p-type and n-type materials and the electrode are not good, a loss of power can be taken out.
This can occur even when the electrode material is selected. Furthermore, the bonding of the electrode at the high-temperature end causes the diffusion of atoms between the thermoelectric material and the electrode material, and in some cases, alloying, or the separation of the electrode or the cracks when the difference in the coefficient of thermal expansion between the electrode material and the electrode material is large. There was a problem.

[0015] The present invention provides a thermoelectric conversion material, particularly an inexpensive and lightweight thermoelectric material.
It is an object of the present invention to provide a thermoelectric conversion element using a Si-based thermoelectric conversion material, which has a configuration in which the thermoelectric conversion efficiency of a Si-based material is significantly increased, and is easily manufactured, and a method for manufacturing the same.

[0016]

Means for Solving the Problems The inventors of the present invention have developed a method of integrating n-type and p-type materials as a method for extracting electric power as a thermoelectric conversion element without impairing the thermoelectric properties of a Si-based thermoelectric conversion material or the like. Focusing on the
In addition to powder metallurgical means such as sintering powder after hot compression molding such as hot pressing, discharge plasma sintering, hot isostatic pressing, or cold compression molding, patterning of resist of powder material on Si substrate I tried with the method of stacking.

[0017] The inventors of the present invention provide an extremely easy integration by interposing an insulating material such as a Si-based or ceramic powder at a portion other than the portion where the pn junction is to be performed.
The loss at the joint is greatly reduced, the thermoelectric conversion efficiency is improved, and the electrodes are made by alternately arranging the materials to produce a sintered body integrated with p / n / p / n / p /. The inventors have found that the loss due to the bonding is almost negligibly small, and that an element can be manufactured in which the bonded portion does not peel or crack due to thermal stress.

Further, the inventors attempted to join the pn junctions located on the high temperature side and the low temperature side when a temperature gradient was given to the thermoelectric conversion element via a dissimilar metal to form an element. A method of inserting metal powder at the interface of p / n powder during powder sintering, and a method of interposing a metal plate at the interface of p / n, joining by the powder metallurgical means, and the integrated element As a result of measuring the voltage and the current, it was found that the electromotive force and the amount of electric power were improved by optimally selecting the metal material, and the present invention was completed.

Furthermore, not only the joining by powder metallurgy, but also the sintered material of the Si-based material, the bulk of the ingot material and the electrode material are heated by resistance heating,
It is possible to join by pressure bonding method such as electric current sintering, hot pressing, baking method using paste material, and even welding method. By selecting the most suitable electrode material, the loss of electrode joining can be reduced. It was also found that the electromotive force and the electric energy were improved.

According to the present invention, there is provided one or more pn junctions integrally formed by interposing an insulating material or interposing an electrode material and an insulating material between an n-type semiconductor material and a p-type semiconductor material. It is a thermoelectric conversion element characterized by the following.

[0021] Further, according to the present invention, the n-type semiconductor powder material and the p-type semiconductor powder material are arranged via a plate-like or powder insulating material or further through an electrode material and integrated by powder metallurgy, or A solid n-type semiconductor material and a p-type semiconductor material are arranged via a plate-like, powdery or paste-like insulating material or further through an electrode material, and are integrated by cold or hot pressing or firing. And forming one or more pn junctions in the integrated thermoelectric conversion element.

Further, the present invention is a thermoelectric conversion element characterized in that different electrode materials are arranged on a high temperature side and a low temperature side when a temperature gradient is given to the element, and a method of manufacturing the same.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a thermoelectric conversion element according to the present invention will be described in detail with reference to the drawings. FIG. 1A shows a case where a direct pn junction is performed by powder metallurgy, and the p-type semiconductor material powder 1 is used.
Sinterable material powders are used as the n-type semiconductor material powder 2 and the insulating material powder 3, respectively.

For example, a p-type semiconductor material powder 1, an n-type semiconductor material powder 2, and an insulating material powder 3 are alternately inserted into a box-shaped mold by using tuning fork-type partition members so that the open sides are alternately replaced. Then, the partition member is removed, a lid is provided on the upper surface, and the mold is compressed in the direction of the arrow toward the center of the mold to form a molded body.

The molded body has a structure in which p-type semiconductor material powders 1 and n-type semiconductor material powders 2 are alternately arranged separated by insulating material powders 3 except for a pn junction scheduled portion 4. Here, by sintering the molded body, an insulating material is integrated between the respective semiconductor materials, and a plurality of pn junctions directly joined by sintering are provided in a connecting direction of the respective semiconductor materials. Is obtained.

In FIG. 1A, three portions of the insulating material powder are
Even if you change to a preformed insulating material plate, insulating material sheet, etc.
It is possible to manufacture a connected-type thermoelectric conversion element having a plurality of direct pn junctions formed by sintering, and a pair-type thermoelectric conversion element having a single direct pn junction can be similarly manufactured.

The manufacturing example shown in FIG. 1B uses a triangular partition member in a box-shaped mold so that the open sides are alternately replaced.
And, in order to prevent the insulating material powder from entering the required tip of the triangular partition member, the p-type semiconductor material powder 1, the n-type semiconductor material powder 2, and the insulating material powder 3 are alternately inserted, and the partition member is removed. Then, it is compressed in the direction of the arrow toward the center of the mold to form a molded body.

The molded body has a structure in which p-type semiconductor material powders 1 and n-type semiconductor material powders 2 are alternately arranged separated by insulating material powders 3 except for a pn junction scheduled portion 4. By sintering this molded body, the insulating material is integrated between the semiconductor materials,
An integrated thermoelectric conversion element having a plurality of pn junctions directly joined by sintering in the connecting direction of each semiconductor material is obtained.

[0029] In the manufacturing example shown in FIG. 2A, an insulating material powder 3 and an electrode material powder 5 are placed between a p-type semiconductor material powder 1 and an n-type semiconductor material powder 2 in a box-shaped mold as shown. 2 and 6, the insulating material powder 3 and the electrode material powders 5 and 6 are inserted in such a way that the insertion positions are alternately switched, and compressed in the direction of the arrow toward the center of the mold, and FIG.
To form a molded body as shown in FIG.

Further, when a temperature gradient in which the lower part of the thermoelectric conversion element completed in the figure is closer to the heat source on the high temperature side and the upper part is on the low temperature side is given, the electrode material powder has a high temperature side 6 and a low temperature side 5. Metal and alloy powders of different materials are used.

By sintering the compact, an insulating material is integrated between the respective semiconductor materials, and a plurality of pn junctions joined via the electrode material by sintering are formed in a plurality of directions in the connecting direction of the respective semiconductor materials. Thus, an integrated thermoelectric conversion element can be obtained.

Further, the insulating material powder 3 and the electrode material powders 5 and 6 are shown in FIG.
In addition to the rectangular shape shown in FIG. 2, as shown in FIG.2C, it is also possible to load a triangular shape between the p-type semiconductor material powder 1 and the n-type semiconductor material powder 2, depending on the amount of the insulating material and the insulating dimensions. Any form can be adopted accordingly.

The manufacturing example shown in FIG. 3A is the same as that of FIG. 1B described above, except that thin plate-shaped electrode materials 7 and 8 are arranged at the pn junction planned portions of the triangular apexes where the insulating material powder is not arranged in FIG. 1B. The other is charged with the insulating material powder 3, and after sintering after being formed into a compression molded body, the insulating material is integrated between the semiconductor materials and sintered through the electrode materials 7 and 8. Integrated thermoelectric conversion element having a plurality of pn junctions joined in the connecting direction of each semiconductor material is obtained. Again, electrode materials 7 and 8 include:
When a temperature gradient in which the lower part of the thermoelectric conversion element completed in the figure is close to the heat source on the high-temperature side and the upper part is on the low-temperature side is given, the electrode materials include metals of different materials on the high-temperature side 8 and the low-temperature side 7, respectively. Alloy is used.

The manufacturing example shown in FIG. 3B shows a p-type semiconductor material 10 and an n-type semiconductor material 11 such as an ingot solidified from a molten alloy in a block shape or a sintered material compressed and molded in a block shape and sintered.
In between, the insulating material 12 and the electrode materials 13 and 14 processed into a plate material are arranged, and they are brought into contact with each other, and are integrated by hot or cold crimping means. An integrated thermoelectric conversion element is obtained in which the materials are integrated and a plurality of pn junctions joined via the electrode material in the connection direction are arranged.

FIG. 3C shows a production example in which a paste-like insulating material 15 and paste-like electrode materials 16 and 17 are provided on one surface of a p-type semiconductor material 10 and an n-type semiconductor material 11 such as the above-mentioned ingot material or sintered material.
Are applied, and these are brought into contact with each other, and are integrated by firing, so that the insulating material is integrated between the respective semiconductor materials, and a plurality of pn junctions joined via the electrode material in the connecting direction are formed. The arranged integrated thermoelectric conversion element is obtained.

In this case as well, when the electrode materials 16 and 17 are given a temperature gradient in which the lower part of the thermoelectric conversion element completed in the figure is closer to the heat source and the upper part is the lower temperature side, the electrode material has a high temperature. The side 17 and the low-temperature side 16 use different metals and alloys. Further, instead of the paste-like insulating material 15 and the electrode materials 16 and 17, it is also possible to use an insulating material powder for sintering and an electrode material powder and to integrate them by means such as current sintering. .

As a method of arranging the semiconductor material to be integrated, in addition to an even-numbered type starting from p-type and ending with n-type, as shown in FIG. 1, p, n, p and n, p, n, p, n, etc. In any case, it is necessary to provide a structure having one or more pn junctions in the connecting portion.

As an integral molding method, a powder metallurgy method, a pressure bonding method, a firing method, a welding method, or the like can be adopted. Powder metallurgy, for example,
A n-type semiconductor powder material of Si-Ge, a p-type semiconductor powder material, and a plate or powder of a metal material are placed individually or simultaneously in a mold or the like having a shape substantially similar to the thermoelectric conversion element in FIG. 1, and the powder is hot-pressed. It can be integrated by powder metallurgical means such as sintering after hot compression molding such as discharge plasma sintering or hot isostatic pressing or cold compression molding.

Further, a sintered material of a Si-based material, a Si-Ge alloy, a smelting material and an electrode material are subjected to a pressure bonding method such as resistance heating, electric current sintering, hot pressing, a firing method using a paste material, Can be pn-joined by a welding method or the like. As the above-mentioned integrated molding method, an optimal method may be selected according to the types and forms of the semiconductor material, the electrode material, and the insulating material.

Further, in addition to the powder metallurgy method described above, a Si substrate, a Si
A method of patterning and stacking a resist of a powder material on a _1-x Ge _x (x <0.20) substrate can be adopted. In particular,
PVD method to evaporate Si and Ge by electron beam heating, SiH ₄ , G
There is the eH ₄ Si, CVD method to stack Ge, etc., it is also possible joining of the pn junction and metal layer through a mask. After the lamination, a heat treatment is performed at 400 to 800 ° C., whereby the laminated film is crystallized and the characteristics are improved.

As the insulating material, any known material capable of electrical insulation can be used. The specific resistance is preferably 10 ² Ω · m or more. A material that can be sintered, pressed, and bonded to a semiconductor material and has a similar thermal expansion coefficient is preferable. Further, when heat is conducted from the insulating material, the temperature gradient of the thermoelectric conversion material becomes small. Therefore, a material having low thermal conductivity is preferable. For example, the semiconductor material is Si-based material, in the case of Si-Ge alloys, can be used Si, Nondobu _{Si-Ge, SiO 2, Si} 3 N 4, BN, SiC, Al 2 O 3, TiN, and various ferrites .

As the electrode material, any material such as a metal and a resin can be used, and it is preferable to use a metal or an alloy which has relatively excellent corrosion resistance and can be easily attached to the thermoelectric conversion material. In particular, it is preferable to use a high melting point metal or alloy for a thermoelectric material exhibiting high characteristics at a high temperature. For example, as the material on the high temperature side of the thermoelectric conversion material, Zr, Au, Ag, Pt, Cu, Ti, Mo, Zn, W, C, and as the material on the low temperature side, Bi, Sn, Ag, Cu, Pt, Al , Au, Fe, Mo, Zn, and Pb are preferred. Further, alloys of these metals or alloys containing these metals can also be used.

The types and combinations of metal materials used on the high temperature side and the low temperature side of the thermoelectric conversion material differ depending on the type of the thermoelectric conversion material. For example, in the case of FeSi ₂ compound, P
t, Cu on the low temperature side, Pt on the high temperature side for Bi ₂ Te ₃ compounds,
When Al and Si _1-x Ge _x (x <0.20) on the low temperature side, P on the high temperature side
t, Al on the low temperature side, etc. are preferred.

In the present invention, any known material can be used as the thermoelectric conversion material. Especially Si-based materials, Si _1-x G
In addition to the thermoelectric conversion material having the composition of e _x (x <0.20), Bi ₂ Te ₃
System materials are preferred.

The Si-based material has a composition of Si _1-x A _x (x <0.20), where A is a group 4 element (Ge, C, Sn), a group 3-5 compound semiconductor, or a group 2-6 compound semiconductor. Is added, and the carrier concentration is controlled to 10 ¹⁷ to 10 ²¹ (M / m ³ ) by a dopant element to be described later. In addition, in the case of Si—Ge, the additive element and the dopant element, and in the case of Si—Ge, a structure in which Ge and the dopant element are segregated at the same time is characterized.

The Si-based material has a carrier concentration in the Si semiconductor of 10
By adjusting the amount of addition of various additive elements such as P, B, and Al, alone or in combination, to ¹⁷ to 10 ²¹ (M / m ³ ), the Seebeck coefficient is extremely large, and the thermoelectric conversion efficiency is significantly increased. It is an inexpensive thermoelectric conversion material that can be enhanced, has high productivity and stable quality.

[0047] In the Si-based material of the present invention, especially in the case of Si-Ge, when Ge is less than 0.05 atomic%, the thermal conductivity is large,
A high figure of merit cannot be obtained, and at 20 atomic% or more, the thermal conductivity slightly decreases.
Is diffused to form a solid solution, so that the high Seebeck coefficient of Si decreases and the figure of merit decreases. Therefore, the preferable content of Ge is in the range of 0.05 or more and less than 20 atomic%. Particularly preferably, it is 3 to 10 atomic%.

In the present invention, the dopant element for converting Si into a P-type semiconductor or an N-type semiconductor is used to reduce the thermal conductivity and electric resistance at a carrier concentration within a required range and to obtain a high Seebeck coefficient. It is to be added. Considering the application of the thermoelectric conversion material, it changes depending on the application such as Seebeck coefficient, electrical conductivity, or thermal conductivity, depending on the application such as the heat source, the use location and form, the current to be handled, the magnitude of the voltage, etc. Therefore, the selected element and the amount of addition can be selected according to the use or the like. The addition amount is preferably 0.001 atomic% to 20 atomic%.

As a dopant element for forming a p-type semiconductor, a p group group (Be, Mg, Ca, Sr, Ba, Zn, Cd, Hg, B, Al, Ga, I
n, Tl), the transition metal element M ₁ group _{(M 1; Y, Mo,} 1 or selected from the group of Zr) or two or more is desirable. Among them, particularly preferred elements are B, Ga, and Al.

The dopant element for forming an n-type semiconductor includes an n group (N, P, As, Sb, Bi, O, S, Se, Te) and a transition metal element M ₂
(M ₂ ; Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Ru, Rh, Pd, Ag, Hf, Ta, W,
Re, Os, Ir, Pt, Au (Fe is 10 atomic% or less), rare earth element group
One or two or more selected from each group of RE (RE; La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu) are desirable. Among them, particularly preferred elements are P, Cu and As.

[0051]

EXAMPLES Example 1 As a raw material, p-type Si _0.95 Ge _0.05 (B0.3at%) and n-type Si
_0.95 Ge _0.05 (P0.4at%) was blended and the ingots of p-type and n-type thermoelectric materials melted in a high-frequency vacuum melting furnace were shake milled and jet milled in nitrogen gas to an average particle size of about 4μm.
Crushed.

Each of the obtained powders is formed into a carbon type as shown in FIG. 1A by joining a p-type semiconductor material powder 1 and an n-type semiconductor material powder 2 to a pn junction scheduled portion 4.
Except for the insulating material powder 3 is loaded so as to be arranged alternately separated by 1500 ~ 1600K × 1h, pressure 25 ~ 100
10 pn junctions integrated by hot press at MPa
Thermoelectric conversion elements were produced at various locations.

The dimensions of the entire device were 5 mm × 75 mm × 15 mm.
Attach electrodes and lead wires to both ends of the element,
The output power was obtained by heating to a high temperature of 873K and applying a temperature gradient of 373K to the other, measuring the generated electromotive force, generated electromotive current and resistance with a digital multimeter. The results are shown in Table 1. Note that the power ratio was compared with the output power of Comparative Example 1 (without an insulating material) described below as 1.

As comparative examples, Table 1 similarly shows measured values when no insulating material was sandwiched (Comparative Example 1) and measured values when joined via a Pt paste (Comparative Example 2).

Example 2 As raw materials, p-type Si _0.95 Ge _0.05 (B 0.3 at%) and n-type Si
_0.95 Ge _0.05 (P0.4at%) was blended, and p-type and n-type thermoelectric conversion material ingots melted by arc melting were pulverized by a stamp mill and a ball mill to an average particle size of about 2 μm. The ball mill was performed in a xylene solvent.

[0056] Each of the obtained powders is loaded with an insulating material powder 3 and electrode material powders 5 and 6 having a particle size of 10 µm between a p-type semiconductor material powder 1 and an n-type semiconductor material powder 2 as shown in Fig. 2A. Insulation material powder 3 and electrode material powders 5 and 6 are loaded so that they are inserted alternately, and are subjected to discharge plasma sintering under the conditions of 1100 to 1573 K × 600 sec, pressure 50 MPa, and thermoelectric conversion with 10 pn junctions An element was manufactured.

The dimensions of the entire device were 5 mm × 75 mm × 15 mm.
An electrode and a lead wire are bonded to both ends of the element, one is heated to a high temperature of 873K, the other is heated to a temperature gradient of 373K, and the generated electromotive force, generated current and resistance are digital multimeters. , And the obtained output power was obtained. The results are shown in Table 2. The power ratio is
The comparison was made assuming that the output power of the following comparative example 4 (without insulating material) was 1.

As comparative examples, measured values when no insulating material was sandwiched (Comparative Example 4) and measured values when joined via a Pt paste (Comparative Example 5) Table 2 similarly shows measured values of an element not passing through a plate (Comparative Example 3).

Example 3 As raw materials, p-type Si _0.95 Ge _0.05 (B0.3 at%) and n-type Si
_0.95 Ge _0.05 (P0.4at%) was blended and the ingots of p-type and n-type thermoelectric materials melted in a high-frequency vacuum melting furnace were shake milled and jet milled in nitrogen gas to an average particle size of about 4μm.
Crushed. Each obtained powder is 5mm × 5mm × 15mm
And hot-pressed at 1573K × 1h at a pressure of 50 MPa.

As shown in FIG. 3C, a paste-like insulating material 15 and a low-temperature side electrode paste 16 are used for the p-type material.
Then, a paste-like insulating material 15 and a high-temperature side electrode paste 17 were applied to the n-type material, and then fired in a vacuum at 1173 K × 30 min to produce a thermoelectric conversion element having 10 pn junctions.

An electrode and a lead wire are joined to both ends of the thermoelectric conversion element, one is heated to a high temperature of 873K, and the other is provided with a temperature gradient of 373K. Measurement was performed with a digital multimeter, and the obtained output power was obtained. The results are shown in Table 3. Note that the power ratio is the output power of the following comparative example 7 (without insulating paste) being 1
Were compared.

As comparative examples, measured values when no insulating paste was interposed (Comparative Example 7) and measured values of an element with an insulating paste interposed at the pn junction but without the electrode paste (Comparative Example 6)
Are also shown in Table 3.

[0063]

【table 1】

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

The thermoelectric conversion element according to the present invention is obtained by integrating an insulating material such as a Si-based or ceramic powder at a portion other than a portion where a pn junction is to be formed by a powder metallurgy method or the like.
The integration is extremely easy, the loss of the pn junction is greatly reduced, the thermoelectric conversion efficiency is improved, and especially the low cost and light weight
The thermoelectric conversion efficiency of the Si-based material can be significantly increased, and a configuration can be provided in which the joint does not peel or crack due to thermal stress.

Further, according to the present invention, the pn junction located on the high temperature side and the low temperature side when a temperature gradient is applied to the thermoelectric conversion element is joined via a dissimilar metal to form an element, so that electromotive force and The electric energy is improved.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory diagrams showing the arrangement of materials showing a method for manufacturing a thermoelectric conversion element according to the present invention, in which direct pn junction is performed by powder metallurgy.

FIG. 2A is an explanatory diagram of material arrangement showing a method for manufacturing a thermoelectric conversion element according to the present invention, in which a pn junction is performed by powder metallurgy with an electrode powder interposed therebetween, and B shows a molded body; C
Indicates a case where the arrangement shapes of the insulating material powder and the electrode powder in A are different.

FIG. 3A is an explanatory diagram of material arrangement showing a method of manufacturing a thermoelectric conversion element according to the present invention, in which a pn junction is performed by a powder metallurgy method with a thin plate electrode interposed therebetween, and B is a method of connecting bulk materials to each other. When the pn junction is performed by the crimping method, C indicates the case where the paste is used as the bulk material.

[Explanation of symbols]

 1 p-type semiconductor material powder 2 n-type semiconductor material powder 3 insulating material powder 4 planned pn junction 5 electrode material powder (low temperature side) 6 electrode material powder (high temperature side) 7 electrode material (low temperature side) 8 electrode material (high temperature side) ) 10 p-type semiconductor material 11 n-type semiconductor material 12 insulating material 13 electrode material (low temperature side) 14 electrode material (high temperature side) 15 paste-like insulating material 16 paste-like electrode material (low-temperature side) 17 paste-like electrode material (high-temperature side) )

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuneka Saigo 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Sumitomo Special Metals Co., Ltd. Yamazaki Works (72) Inventor Shunichi Haruyama 3 Fushiodai, Ikeda-shi, Osaka Chome 5-8

Claims (8)

[Claims] 1. A thermoelectric conversion element which is integrated between an n-type semiconductor material and a p-type semiconductor material with an insulating material interposed therebetween and has one or more pn junctions in a connecting direction. 2. A thermoelectric conversion element which is integrated between an n-type semiconductor material and a p-type semiconductor material with an electrode material and an insulating material interposed therebetween and has one or more pn junctions in a connecting direction. 3. The thermoelectric conversion element according to claim 1, wherein the integration is performed by a powder metallurgy method, a pressure bonding method, a firing method, or welding. 4. The thermoelectric conversion element according to claim 3, wherein the electrode material is different between a high temperature side and a low temperature side when a temperature gradient is given. 5. An n-type semiconductor powder material and a p-type semiconductor powder material are arranged via a plate or powder insulating material or further via a plate or powder electrode material and integrated by powder metallurgy to obtain One or more integrated thermoelectric conversion elements
A method for manufacturing a thermoelectric conversion element for forming a pn junction. 6. A bulk n-type semiconductor material and a p-type semiconductor material are arranged via a plate-like or paste-like insulating material or further via a plate-like or paste-like electrode material, and integrated by a crimping method. A method for producing a thermoelectric conversion element, wherein one or more pn junctions are formed in an integrated thermoelectric conversion element. 7. An integrated thermoelectric conversion device in which a bulk n-type semiconductor material and a p-type semiconductor material are arranged via a paste-like insulating material or a paste-like electrode material, and are integrated by a firing method. A method for manufacturing a thermoelectric conversion element in which one or more pn junctions are formed in the element. 8. A different electrode material is arranged on each of a high temperature side and a low temperature side when a temperature gradient is given as an element.
8. A method for producing a thermoelectric conversion element according to claim 1.