Agency of Industrial Science and Technology

Agency of Industrial Science and Technology Ministry of International

Other

Sumitomo Electric Industries, Limited

Ministry of International Trade & Industry

National Institute of Advanced Technology

Ichiro Matsubara

Ryoji Funahashi

Hiroshi Ishikawa

Hiroshi Yamashita

Satoshi Sodeoka

Kazuo Ueno

Makoto Kinoshita

Toru Ogura

Hideo Tanigawa

Tomoji Kawai

Osamu Yamada

Mitsue Koizumi

Yoshinari Miyamoto

Masahiro Shikano

Manshi Ooyanagi

Kimiaki Tanihata

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.

Method for production of superconducting polycrystalline wire rod

There is disclosed a single crystalline fibrous superconductive composition represented by the atomic compositional formula: Bi.sub.2 Sr.sub.2 CaCu.sub.2 M.sub.X O.sub.Y wherein 0&lt;X&lt;0.5; 7.8&lt;Y&lt;8.5; and M is at least one member selected from the group consisting of Pb, Sn, Sb, In, Cd, Ga, Ge, K, Li, and Na. This composition is prepared by a process comprising the step of mixing source material with one another to prepare a mixture having an atomic compositional ratio: Bi=1.00, Sr=0.5.about.2.0, Ca=0.5.about.5.0, Cu=1.0.about.7.0, and M=0.1.about.1.0, wherein M is at least one member selected from the group consisting of Pb, Sn, Sb, In, Cd, Ga, Ge, K, Li, and Na, the step of melting the mixture to prepare a molten material having an atomic compositional ratio: Bi=1.00, Sr=0.5.about.2.0, Ca=0.5.about.5.0, Cu=1.0.about.7.0, M=0.1.about.1.0, and O=3.5.about.8.8, the step of quenching the molten material to prepare a solid material, and the step of heat-treating the solid material in a stream of a gas containing oxygen.

Single crystalline fibrous superconductive composition and process for

A process for producing a fibrous crystal or single crystal of a superconductor comprising bismuth, strontium, calcium, copper, lead and oxygen, having an atomic composition ratio represented by the formula Bi.sub.2-x Pb.sub.x Sr.sub.1.9-2.1 Ca.sub.1.9-2.1 Cu.sub.3 o.sub.y wherein 0&lt;.times.&lt;0.4 and 10.0&lt;y&lt;11.0, and having a Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.10 structure (2223 structure).

Superconductor crystal and process for preparing the same

Process for preparing NbN superconducting material, characterized in that a bulk Nb is placed in powder including at least one metal which can be nitriding-burned, and then the powder is heated to be nitriding-burned in pressurized N.sub.2 atmosphere so that the bulk Nb is nitrided by the nitriding-burning of the powder.

Growing community of inventors

Ikeda, Japan

Ichiro Matsubara