JPH01183863A - Laminated thermoelectric element - Google Patents

Abstract

PURPOSE:To make it possible to use a semiconductor ceramic material, whose sintering has been hard as a thin plate, by baking layers in the state of semiconductor ceramic green sheets with ceramic insulator green sheets as a unitary body. CONSTITUTION:N-type ceramic insulator green sheets 4a-4f area provided in the region other than electrode forming parts 3a-3d between P-type semiconductor ceramic green sheets 1a-1c and N-type semiconductor ceramic green sheets 2a and 2b. The sheets are baked as a unitary body. Since the P-type semiconductor layers, the N-type semiconductor layers and the insulator layers are all laminated in the green sheet states, they are not broken down or cracked when they are laminated and compressed. Thus, each layer can be made thin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Al Industrial Field of Application) The present invention relates to a laminated thermoelectric element formed by alternately laminating a plurality of p-type semiconductor ceramic layers and n-type semiconductor ceramic layers.

(bl Conventional technology) Conventionally, as thermoelectric materials, Bi, Te, , FeSi, 5i
-Ge, etc. are known. Furthermore, when constructing a thermoelectric element using these materials, a laminated structure is used to increase the thermoelectromotive force.

Ic) Problems to be Solved by the Invention By the way, if the figure of merit of the thermoelectric element is Z, it is expressed by the following relationship.

Z=α2/ρ where α is the Seebeck coefficient, K is the thermal conductivity, and ρ is the specific resistance.

Since the thermoelectric materials used in the conventional thermoelectric elements have a small ρ, they are excellent for power applications such as electronic cooling elements or electronic heating elements that utilize the Peltier effect. However, when used as a thermal sensor, it is important to use a thermoelectric material with a large Seebeck coefficient α to increase sensitivity in order to utilize the electromotive force.

The Seebeck coefficient α of the above conventional thermoelectric material is 200 to 60.
It is only about 0 μV/. Although some semiconductor ceramic materials have a larger Seebeck coefficient than the thermoelectric materials, there have been no examples of such materials being effectively utilized. The reason for this is that it is difficult to manufacture thin sintered bodies, and for example, when bonding multiple ceramic sintered plates together,
This is because there are problems such as destruction during the process.

An object of the present invention is to provide a laminated thermoelectric element that uses semiconductor ceramic as a thermoelectric material and that can be easily multilayered to construct, for example, a highly sensitive thermal sensor.

+d1 Means for Solving the Problem The laminated thermoelectric element of the present invention is a laminated thermoelectric element in which a plurality of n-type semiconductor ceramic layers and n-type semiconductor ceramic layers are alternately laminated. It is characterized in that an insulating ceramic green sheet is interposed between the n-type semiconductor ceramic green sheets in the area excluding the electrode forming portion, and is integrally fired (81). An insulating ceramic green sheet is interposed between the sheet and the n-type semiconductor ceramic green sheet in a region excluding the electrode forming portion, that is, a region insulating between the two-handed conductor ceramic layers.Therefore, the n-type semiconductor ceramic green sheet is integrally fired.
The type semiconductor ceramic layer and the n-type semiconductor ceramic layer are integrated through an insulating ceramic layer. Here, since the p-type semiconductor layer, the n-type semiconductor layer, and the insulator layer are all laminated in the form of green sheets, they will not be destroyed or cranked during stacking and pressurization. Therefore, each layer can be made thinner.

As p-type semiconductor ceramics, Nip, MnO, co
o, a material made into a semiconductor by doping one or more types of FeO mainly with Li2Q can be used. Also, n
As the type semiconductor ceramic, BaTi0. or BaT
iO3 to 5rTi03, Ca T t O31P b
A material obtained by doping a rare earth element, NbzOs, or Ta20 into a material in which one or more types of TiO3 are dissolved in solid solution to make it a semiconductor can be used. Note that the p-type semiconductor ceramic and the n-type semiconductor ceramic described above can be converted into semiconductors by firing in air.

The problem with integral firing is what material to use for the insulating layer. The insulating layer needs to be made of a material that does not significantly interdifuse with the p-type semiconductor layer and the n-type semiconductor layer and has high bonding properties. Therefore, as an insulating ceramic, ZrO2Ti0z
AO(A:Ni, Mn, Co, Fe)-A1
203-Yz Ox system can be used. Here Z
r0g suppresses reactivity, so Alz 03 , Y20
3 is an additive for lowering the sintering temperature. As the electrode material, Pt, Pd, and Ag-Pd can be used. (f) Example As the p-type semiconductor ceramic, Ni099.5mo1%
Using a material doped with Li and O at 5 mo1%, n
BaTi0: +80.0 as type semiconductor ceramic
A material obtained by doping 0.5m01% of Y2O3 into a material in which 19°5mo1% of CaTi0= was dissolved in mo1% was used. In addition, as an insulating ceramic, Zr0t 1
5moJ%.

Tie□ 30mo1%, Ni0N103O%.

Using materials consisting of 25 moJ% of Al2O3, a binder was added to each material, and a green sheet was formed by a doctor blade method.

FIG. 1 shows a laminated state of an n-type semiconductor ceramic green sheet, an n-type semiconductor ceramic green sheet, and an insulator ceramic green sheet. In the figure l
a, lb, and lc are n-type semiconductor ceramic green sheets, and 2a and 2b are n-type semiconductor ceramic green sheets, respectively. Conductive pastes 3a, 3b, 3c, and 3d consisting of Ag:Pd=1:9 are printed on these semiconductor ceramic green sheets in advance.

After the green sheets are laminated and fired, these conductive pastes act as an electrode that electrically connects the n-type semiconductor ceramic layer and the n-type semiconductor ceramic layer at one end. Further, in the figure, 4a to 4f are insulating ceramic green sheets, which are arranged between the semiconductor ceramic green sheets in a region other than the area where the conductive paste is formed.

After laminating and pressurizing each of the above green sheets, N2-0□
Or fired at 1300''C in air.

After firing, an extraction electrode was formed on the exposed portion of the semiconductor ceramic on the outside, and a laminated thermoelectric element was obtained by slicing into a predetermined size. FIG. 2 shows the cross-sectional structure of the completed laminated thermoelectric element. In this way, the n-type semiconductor ceramic layers 1a, lb, lc and the n-type semiconductor ceramic layers 2a, 2b
The layers are electrically connected by electrodes 3a, 3b, 3c, 3d, and the semiconductor ceramic layers and the outer part are connected by insulating ceramic layers 4a, 4b, 4c, 4d, 4.
e, electrically insulated by 4f. In addition, 5a and 5b
indicates the extraction electrode.

For explanation purposes, FIGS. 1 and 2 show an example in which there are three n-type semiconductor layers and two n-type semiconductor layers, but one p-type and one n-type semiconductor layer each.
The temperature characteristics of the Seebeck coefficient of the thermoelectric element sliced into 10 x 2 x 1 m slices as the zero layer are shown in the table.

As shown in the table, the p-type semiconductor ceramic in the example has a negative absolute value of the Seebeck coefficient with respect to temperature,
The n-type semiconductor ceramic has a positive characteristic in terms of the absolute value of the Seebeck coefficient with respect to temperature. For this reason, the thermoelectric element, which is a laminate of amphibically conductive ceramics, has substantially flat temperature characteristics with positive and negative cancellation.

fg1 Effects of the Invention According to the present invention, when a plurality of n-type semiconductor ceramic layers and n-type semiconductor ceramic layers are alternately laminated, the semiconductor ceramic green sheets are integrally fired together with the insulator ceramic green sheets. Therefore, it is possible to use a semiconductor ceramic material with a large Seebeck coefficient, which has conventionally been difficult to sinter into a thin plate, and a highly sensitive thermal sensor can be constructed. Furthermore, even if each layer is made thinner, there will be no breakage or cranking during manufacturing, and mass production can be achieved at low cost. Furthermore, since the entire device can be miniaturized, a thermoelectric device with a small heat capacity can be easily obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a state before lamination of a laminated thermoelectric element according to an embodiment of the present invention, and FIG. 2 is a sectional view of the completed laminated thermoelectric element. la, lb, lc p-type semiconductor ceramic green sheet and its sintered body, 2a, 2b-n-type semiconductor ceramic and its sintered body, 3a, 3b, 3c, 3d-conductive paste and electrode by baking it, 4a, 4b , 4c, 4d, 4e,
4f - Insulator ceramic green sheet and its sintered body, 5a, 5b - Extraction electrode.

Claims (1)

[Claims] (1) In a laminated thermoelectric element in which a plurality of p-type semiconductor ceramic layers and n-type semiconductor ceramic layers are alternately laminated, there is a region between the p-type semiconductor ceramic green sheet and the n-type semiconductor ceramic green sheet, excluding the electrode forming part. A laminated thermoelectric element is made by interposing an insulating ceramic green sheet and integrally firing it.