National Institute of Advanced Industrial Science and Technology

Agency of Industrial Science and Technology

Agency of Industrial Science and Technology Ministry of International

Ministry of International Trade & Industry

National Institute of Advanced Technology

Ryoji Funahashi

Ichiro Matsubara

Hiroshi Ishikawa

Satoshi Sodeoka

Kazuo Ueno

Masahiro Shikano

Jun Akedo

Sou Baba

Masashi Mikami

Toshiyuki Mihara

Emmanuel Guilmeau

This thermoelectric conversion module is formed by electrically connecting, by a conductive member, one end of an n-type thermoelectric conversion element having a negative Seebeck coefficient and having a half-Heusler structure to one end of a p-type thermoelectric conversion element containing an oxide having a positive Seebeck coefficient at a temperature of 25° C. or higher. The conductive member is connected to the n-type thermoelectric conversion element and the p-type thermoelectric conversion element through a connection layer containing a conductive metal comprising silver, and the connection layer is characterized by further containing an oxide to reduce the bond resistance between the n-type thermoelectric conversion element and/or the p-type thermoelectric conversion element.

Thermoelectric conversion module

The present invention provides an electrically conductive paste for connecting thermoelectric materials, the paste comprising a specific powdery oxide and at least one powdery electrically conductive metal selected from the group consisting of gold, silver, platinum, and alloys containing at least one of these metals. By connecting a thermoelectric material to an electrically conductive substrate with the electrically conductive paste of the invention, a suitable electroconductivity is imparted to the connecting portion of the thermoelectric element. Further, the thermal expansion coefficient of the connecting portion can be made close to that of the thermoelectric material. Therefore, even when high-temperature power generation is repeated, separation at the connecting portion is prevented and a favorable thermoelectric performance can be maintained.

Conductive paste for connecting thermoelectric conversion material

The present invention provides a thermoelectric element in which a thin film of p-type thermoelectric material and a thin film of n-type thermoelectric material, which are formed on an electrically insulating substrate, are electrically connected, in which the p-type thermoelectric material and the n-type thermoelectric material are selected from specific complex oxides with a positive Seebeck coefficient and specific complex oxides with a negative Seebeck coefficient, respectively. The present invention also provides a thermoelectric module using the thermoelectric element(s) and a thermoelectric conversion method. In the thermoelectric element of the present invention, since a p-type thermoelectric material and an n-type thermoelectric material are formed into a thin film on an electrically insulating substrate, the thermoelectric element of the invention can be formed on substrates having various shapes, thereby providing thermoelectric elements having various shapes.

Thermoelectric conversion element and thermoelectric conversion module

The present invention provides a novel complex oxide capable of achieving high performance as a p-type thermoelectric material. The complex oxide comprises a layer-structured oxide represented by the formula BiPbMCOMOwherein Mis one or more elements selected from the group consisting of Na, K, Li, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Ca, Sr, Ba, Al, Y, and lanthanoids; Mis one or more elements selected from the group consisting of Ti, V, Cr, Mn, Fe, Ni, Cu, Mo, W, Nb, Ta, and Ag; 1.8&#x2266;a&#x2266;2.5; 0&#x2266;b&#x2266;0.5; 1.8&#x2266;c&#x2266;2.5; 1.6&#x2266;d&#x2266;2.5; 0&#x2266;e&#x2266;0.5; and 8&#x2266;f&#x2266;10; and at least one interlayer component selected from the group consisting of F, Cl, Br, I, HgF, HgCl, HgBr, HgI, TlF, TlCl, TlBr, TlI, BiF, BiCl, BiBr, BiI, PbF, PbCl, PbBr, and PbI. The interlayer component being present between layers of the layer-structured oxide.

Complex oxide having p-type thermoelectric characteristics

The present invention provides a complex oxide having a composition represented by the formula LaMNiOor (LaM)NiO(wherein M is at least one element selected from the group consisting of Na, K, Li, Zn, Pb, Ba, Ca, Al, Nd, Bi and Y, and 0.01&#x2266;&#xd7;&#x2266;0.8), the complex oxide having a negative Seebeck coefficient at 100&#xb0; C. or higher. This complex oxide is a novel material which exhibits excellent properties as an n-type thermoelectric material.

Complex oxide having n-type thermoelectric characteristics

The present invention provides a method by which an oxide material having excellent thermoelectric conversion performance can be produced by a simple process. Specifically, the present invention provides a method for producing a composite oxide single crystal in which a mixture of raw substances including a Bi-containing substance, a Sr-containing substance, a Ca-containing substance, a Co-containing substance and a Te-containing substance, or a mixture of raw substances also including a Pb-containing substance in addition to the above-mentioned substances, is heated in an oxygen-containing atmosphere at a temperature below the melting point of any of the raw substances. The composite oxide single crystal produced by the method of the present invention is a ribbon-shaped fibrous single crystal that is about 10 to 10,000 &#x3bc;m long, about 20 to 200 &#x3bc;m wide, and about 1 to 5 &#x3bc;m thick. According to the method of the present invention, a composite oxide single crystal with excellent thermoelectric conversion performance can be produced simply by heating a mixture of raw substances at a relatively low temperature, below the melting point of any of the raw substances, meaning that a relatively easy and safe heat treatment operation can be performed, which contributes to cost reduction.

Method for producing single crystal of composite oxide

This invention provides a complex oxide comprising the features of : (i) being represented by the formula:(A B M ) Co O wherein A and B are elements differing from each other, each represents Ca, Sr or Ba, M represents Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb or Lu, 1.7&lE;x&lE;2, and 3.8&lE;y&lE;5, (ii) having a Seebeck coefficient of 100 &mgr;V/K or more at a temperature of 100 K (absolute temperature) or higher and (iii) having an electrical resistivity of 10 m&OHgr;cm or less at a temperature of 100 K (absolute temperature) or higher. The complex oxide of the invention is a material composed of low-toxicity elements existing in large amounts, the material having superior heat resistance and chemical durability and a high thermoelectric conversion efficiency in a temperature range of 600 K or higher which falls in the temperature range of waste heat.

Complex oxide having high thermoelectric conversion efficiency

This invention provides a complex oxide comprising the features of: (i) being represented by the formula: (A B M ) Co O wherein A and B are elements differing from each other, each represents Ca, Sr or Ba, M represents Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb or Lu, 1.7&lE;x&lE;2, and 3.8&lE;y&lE;5, (ii) having a Seebeck coefficient of 100 &mgr;V/K or more at a temperature of 100 K (absolute temperature) or higher and (iii) having an electrical resistivity of 10 m&OHgr;cm or less at a temperature of 100 K (absolute temperature) or higher. The complex oxide of the invention is a material composed of low-toxicity elements existing in large amounts, the material having superior heat resistance and chemical durability and a high thermoelectric conversion efficiency in a temperature range of 600 K or higher which falls in the temperature range of waste heat.

This invention provides a complex oxide comprising the features of: (i) being represented by the formula: Ca RE Co O wherein RE is a rare earth element, 0&lE;x&lE;0.5 and 8.5&lE;y&lE;10, (ii) having a Seebeck coefficient of 100 &mgr;V/K or more at a temperature of 300&deg; C. or higher, and (iii) having an electric conductivity of 10 S/m or more at a temperature of 300&deg; C. or higher. The complex oxide is composed of low-toxicity elements, excellent in heat resistance and chemical durability and high in thermoelectric conversion efficiency.

Complex oxide having high seebeck coefficient and high electric conductivity

A method for the production of a superconducting oxide tape having a Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.10 (Bi-2223) structure interposed between silver sheets, which method consists essentially of preparing a sandwich structure having interposed between silver sheets a molded layer of a superconducting oxide precursor powder consisting essentially of Bi, Pb, Sr, Ca, Cu, and O obtained from a raw material substance composed of, in atomic composition ratio, 1.00 of Bi, 0-0.2 of Pb, 0.9-1.1 of Sr, 0.9-1.1 of Ca and 1.3-1.7 of Cu, and O, heating the sandwich structure in an atmosphere consisting of oxygen and an inert gas, having an oxygen partial pressure in the range of 0-5%, and kept at a temperature in the range of 830-850.degree. C., thereby melting the molded layer, then causing the atmosphere to retain the heating temperature and meanwhile increasing the oxygen partial pressure, thereby inducing precipitation of crystal grains possessing a Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.8 (Bi-2212) structure and excelling in orientation, and subsequently maintaining the oxygen partial pressure and temperature at the time of precipitation of the crystal grains, thereby transforming the structure into the (Bi-2223) structure while retaining the particle diameter of the crystal grains and the state of orientation, and superconducting oxide tape produced by the method.

Method for production of superconducting oxide tape and superconducting

This invention concerns a method for the production of an oxide superconducting tape material having a composition of Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.8, which method consists essentially of forming a sandwich structure comprising a layer formed of a superconducting powder consisting essentially of Bi, Sr, Ca, Cu, and O and having an essential structure of Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.8 and silver sheet layers, the superconducting powder layer being interposed between the silver sheet layers, heating the sandwich structure at a temperature in the range of 810.degree.-910.degree. C. in an atmosphere consisting of oxygen and an inert gas and having an oxygen partial pressure in the range of 0-90%, thereby melting the superconducting powder layer, and then elevating the oxygen partial pressure of the atmosphere while retaining the same heating temperature, thereby crystallizing the molten superconducting powder layer.

Method for production of B.sub.i -2212 superconducting tape material

A method for the production of a superconducting polycrystalline wire rod having all the crystal (a, b, c) axes thereof aligned is disclosed, which consists of a step of arraying a plurality of superconducting whiskers of a composition of Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.8 (Bi-2212 phase) in such a manner as to parallellize the fiber axes of the whiskers and then aligning all the crystal axes of the superconducting whiskers with parallellized fiber axes and a step of heat-treating the resultant whiskers.

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Ikeda, Japan

Ryoji Funahashi