TOP > 外国特許検索 > Superconducting compound and method for producing the same

Superconducting compound and method for producing the same

外国特許コード F110005257
整理番号 BE06008WO
掲載日 2011年8月29日
出願国 アメリカ合衆国
出願番号 86594009
公報番号 20110002832
公報番号 8435473
出願日 平成21年2月17日(2009.2.17)
公報発行日 平成23年1月6日(2011.1.6)
公報発行日 平成25年5月7日(2013.5.7)
国際出願番号 JP2009052714
国際公開番号 WO2009104611
国際出願日 平成21年2月17日(2009.2.17)
国際公開日 平成21年8月27日(2009.8.27)
優先権データ
  • 特願2008-035977 (2008.2.18) JP
  • 2009JP052714 (2009.2.17) WO
発明の名称 (英語) Superconducting compound and method for producing the same
発明の概要(英語) Disclosed is a superconducting compound which has a structure obtained by partially substituting oxygen ions of a compound, which is represented by the following chemical formula; LnTMOPh [wherein Ln represents at least one element selected from Y and rare earth metal elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), TM represents at least one element selected from transition metal elements (Fe, Ru, Os, Ni, Pd and Pt), and Pn represents at least one element selected from pnictide elements (N, P, As and Sb)] and has a ZrCuSiAs-type crystal structure (space group P4/nmm), with at least one kind of monovalent anion (F-, Cl- or Br-).
The superconducting compound alternatively has a structure obtained by partially substituting Ln ions of the compound with at least one kind of tetravalent metal ion (Ti4+, Zr4+, Hf4+, C4+, Si4+, Ge4+, Sn4+ or Pb4+) or a structure obtained by partially substituting Ln ions of the compound with at least one kind of divalent metal ion (Mg2+, Ca2+, Sr2+ or Ba2+).
The Tc of the superconducting compound is controlled in accordance with the ion substitution amount.
従来技術、競合技術の概要(英語) BACKGROUND ART
Since a superconducting phenomenon was discovered with respect to mercury in 1911, superconductivity has been found out with respect to many compounds and has been practiced in the form of, e.g., superconducting magnets and magnetic sensors (SQUID).
Further, after discovery of a high-temperature superconductor (i.e., perovskite-type copper oxide), research and development of materials have been intensively performed aiming at room-temperature superconductors, and superconducting compounds having superconducting transition (critical) temperature (Tc) of 100K or higher have been found out.
Understanding of the superconductivity developing mechanism in the perovskite-type copper oxide has also been progressed (e.g., Non-Patent Documents 1 and 2).
Further, as compounds containing transition metal ions other than copper or as novel compounds, Sr2RuO4 (Tc=0.93K) (Non-Patent Document 3), magnesium diboride (Tc=39K) (Non-Patent Document 4 and Patent Document 1), Na0.3CoO2.1.3H2O (Tc=5K) (Non-Patent Document 5 and Patent Documents 2 and 3), etc. have been newly found out.
It is known that a strongly-correlated electron system compound exhibiting a greater interaction between conduction electrons in comparison with a conduction band width becomes a superconductor having a higher Tc at a higher possibility when the number of d-electrons has a specific value.
The strongly-correlated electron system is realized in layered compounds having transition metal ions in skeleton structures.
In many of those layered compounds, electrical conductivity is similar to that of a Mott insulator and an antiferromagnetic interaction acts between electron spins so as to array the electron spins in an antiparallel relation.
However, regarding La2CuO4 as one perovskite-type copper oxide, for example, it is confirmed that, in La2-xSrxCuO4 which is obtained by adding Sr2+ to the La3+ site and by substituting part of La with Sr, the compound comes into an itinerant electron state exhibiting metallic conductivity when a value of x is in the range of 0.05 to 0.28, a superconductor state is observed at low temperature, and maximum Tc=40K is obtained at x=0.15 (Non-Patent Document 6).
Recently, the inventors have found out that new strong electron correlation compounds containing Fe as a main component, i.e., LaOFeP and LaOFeAs, are superconductors, and have filed a patent application (Patent Document 4 and Non-Patent Document 7).
More specifically, in a strong electron correlation system, an itinerant electron state exhibiting metallic conductivity is generated when the number of d-electrons has a specific value, and there occurs transition to a superconducting state at a particular temperature (superconducting transition temperature) or below when the temperature is lowered.
Further, Tc of such a superconductor is changed over the range of 5K to 40K depending on the number of conduction carriers.
Moreover, in conventional superconductors such as Hg and Ge3Nb, electron pairs (Cooper pairs) attributable to heat fluctuation (lattice vibration) of crystal lattices are regarded as developing a superconductivity generating mechanism (BCS mechanism).
On the other hand, regarding superconductivity of the strong electron correlation system, electron pairs attributable to heat fluctuation of electron spins are regarded as developing a superconductivity generating mechanism.
Since then, it has been found out that LaONiP is also a superconductor (Non-Patent Documents 8 to 10).
In the above-mentioned superconducting compounds, electron pairs are in a spin singlet state where respective electron spins are arrayed antiparallel to each other.
In Sr2RuO4 (Tc=0.93K) (Non-Patent Document 3), etc., however, superconductivity attributable to spin triplet electron pairs in which electron spins of the electron pairs are arrayed parallel to each other has been lately found out.
Such a phenomenon is presumably based on the fact that those spin pairs exhibit a ferromagnetic interaction between their electron spins (i.e., an interaction to align the spins parallel to each other).
For that type of superconductor, it is considered that a critical magnetic field at which the superconducting state is broken by a magnetic field is strong.
Accordingly, that type of superconductor is superior when it is used in a ferromagnetic field (for example, when it is used as an inner coil in the case of generating a magnetic field in tandem).
Non-Patent Document 1: Nobuo Tsuda, Keiichiro Nasu, Atushi Fujimori, and Kiichi Shiratori, revised "Denki Dendosei Sankabutsu (Electrically Conductive Oxides)", pp. 350-452, Shokabo Publishing Co., Ltd., (1993)
Non-Patent Document 2: Sadamichi Maekawa, Oyo Butsuri (Applied Physics), Vol. 75, No. 1, pp. 17-25, (2006)
Non-Patent Document 3: Y. Maeno, H. Hashimoto, K. Yoshida, S. Nishizaki, T, Fujita, J. G. Bednorz, F. Lichtenberg, Nature, 372, pp. 532-534 (1994)
Non-Patent Document 4: J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani, and J. Akimitsu, Nature, 410, pp. 63-64, (2001)
Non-Patent Document 5: K. Takada, H. Sakurai, E. Takayama-Muromachi, F. Izumi, R. A. Dilanian, T. Sasaki, Nature, 422, pp. 53-55, (2003)
Non-Patent Document 6: J. B. Torrance et al., Phys. Rev., B40, pp. 8872-8877, (1989)
Non-Patent Document 7: Y. Kamihara et al., J. AM. CHEM. SOC., (Published on Web Jul. 15, 2006), 128, 10012-10013 (2006)
Non-Patent Document 8: T. Watanabe et al., Inorganic Chemistry, 46(19) (2007) 7719-7721 (Published on Web 17 Aug. 2007)
Non-Patent Document 9: T. Watanabe et al., Extended Abstracts (The 68th Autumn Meeting, 2007); The Japan Society of Applied Physics, No. 1, P. 275, 4gamma -ZE-2 (2007)
Non-Patent Document 10: M. tegel et al., Solid State Science, 10 (2008)193-197 (Published on Web 2 Sep. 2007)
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2002-211916
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2004-262675
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2005-350331
Patent Document 4: Japanese Unexamined Patent Application Publication No. 2007-320829

特許請求の範囲(英語) [claim1]
1. A method for producing the superconducting compound, comprising: dehydrating La2O3 by heating in air, thereby obtaining anhydrous La2O3;
mixing La metal, TM metal, and Ph element in a ratio of 1:3:3 to obtain a first mixture, wherein TM is one or more selected from Fe, Ru, Os, Ni, Pd, and Pt; and Ph is one or more pnictide elements selected from N, P, As, and Sb, and sintering the obtained first mixture in a dry inert gas atmosphere, thereby obtaining sintered mixture 1 including LaPh, TM2Ph, and TMPh;
replacing 4-20 mol % of anhydrous La2O3 with mixed powder of LaF3 and La metal in a ratio of 1:1, thereby obtaining mixture 2 including La2O3, LaF3 and La metal; and
mixing the sintered mixture 1 and the mixture 2 such that molar ratio of La and TM becomes 1:1 to obtain a third mixture, and sintering the obtained third mixture at 1100-1250 deg. C. in an inert gas atmosphere, thereby obtaining a compound, which is represented by a chemical formula of LaTMOPh, oxygen ions of which are substituted with 4-20 mol % F- ions, forming a superconducting compound of which superconducting transition temperature is controlled in accordance with an ion substitution amount; wherein the superconducting compound has a maximum superconducting transition temperature of 25K or higher.
[claim2]
2. The method for producing the superconducting compound according to claim 1, wherein the LaTMOPh is polycrystalline LaFeOAs and has a maximum superconducting transition temperature of 26K.
[claim3]
3. The method for producing the superconducting compound according to claim 1, wherein the LaTMOPh is polycrystalline SmFeOAs and has a maximum supercoding transition temperature of 55K.
  • 発明者/出願人(英語)
  • HOSONO HIDEO
  • KAMIHARA YOICHI
  • HIRANO MASAHIRO
  • KAMIYA TOSHIO
  • YANAGI HIROSHI
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
国際特許分類(IPC)
米国特許分類/主・副
  • 423/263
  • 423/301
  • 423/306
  • 423/385
  • 423/593.1
  • 423/594.1
  • 423/594.3
  • 423/594.7
  • 423/601
  • 423/617
  • 505/777
  • 505/810
参考情報 (研究プロジェクト等) ERATO/SORST Exploring and developing applications for active functions utilizing nanostructure embedded in transparent oxides AREA
ライセンスをご希望の方、特許の内容に興味を持たれた方は、問合せボタンを押してください。

PAGE TOP

close
close
close
close
close
close