Novel thermoelectrics emerging from multinary freedoms of clathrates encapsulating rare-earths and alkaline metals

2009 Fiscal Year Final Research Report

• Project/Area Number: 18204032
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Hiroshima University
• Principal Investigator: TAKABATAKE Toshiro Hiroshima University, 大学院・先端物質科学研究科, 教授 (40171540)
• Co-Investigator(Kenkyū-buntansha): SUZUKI Takashi 広島大学, 大学院・先端物質科学研究科, 教授 (00192617) ; UDAGAWA Masayuki 広島大学, 大学院・総合科学研究科, 教授 (70144889) ; UMEO Kazunori 広島大学, 自然科学研究支援開発センター, 准教授 (10223596) ; SHIMADA Kenya 広島大学, 放射光科学研究センター, 准教授 (10284225)
• Project Period (FY): 2006 – 2009
• Keywords: 熱電変換 / 熱伝導 / 格子振動 / エネルギー効率化 / 超音波物性

Research Abstract

Intermetallic clathrates have high potential as thermoelectric converters because of the glass-like thermal conductivity in spite of the three dimensional crystal structure. To understand the mechanism of the reduced thermal conductivity, we have studied type-I clathrates encapsulating alkaline-earth and rare-earth atoms by means of structural refinement, thermal, ultrasonic, Raman scattering and photoemission measurements. It is revealed that the guest in a relaxed space inside the cage can rotate among off-center sites and this motion strongly scatters acoustic phonons to reduce the thermal conductivity.

Research Products

• [Journal Article] Off-center rattling modes and glasslike thermal conductivity in the type-I clathrate Ba8Ga16Sn30 (2010)
  • Author(s): K. Suekuni, Y. Takasu, T. Hasegawa, N. Ogita, M. Udagawa, M.A. Avila, T. Takabatake
  • Journal Title: Phys. Rev. B 81205207 Pages: 1-5
  • Peer Reviewed
• [Journal Article] Interplay between thermoelectric and structural properties of type-I clathrate K8Ga8Sn38 single crystals (2010)
  • Author(s): T. Tanaka, T. Onimaru, K. Suekuni, S. Mano, H. Fukuoka, S. Yamanaka, T. Takabatake
  • Journal Title: Phys. Rev. B 81165110 Pages: 1-6
  • Peer Reviewed
• [Journal Article] Multiple ferromagnetic structures in an off-center rattling system Eu8Ga16Ge30 (2010)
  • Author(s): Onimaru, S. Yamamoto, M.A. Avila, K. Suekuni, T. Takabatake
  • Journal Title: J. Phys. : Conf. Ser 200022044 Pages: 1-4
  • Peer Reviewed
• [Journal Article] Direct verification of Ga-Ga bond avoidance in the type-I clathrate Ba8Ga16Sn30 from its x-ray absorption fine structure (2009)
  • Author(s): M. Kozina, F. Bridges, Y. Jiang, M.A. Avila, K. Suekuni, T. Takabatake
  • Journal Title: Phys. Rev. B 80212101 Pages: 1-4
  • Peer Reviewed
• [Journal Article] Optical conductivity of rattling phonons in type-I clathrate Ba8Ga16Ge30 (2009)
  • Author(s): T. Mori, S. Goshima, K. Iwamoto, S. Kushibiki, H. Matsumoto, N. Toyota, K. Suekuni, M.A. Avila, T. Takabatake, T. Hasegawa, N. Ogita, M. Udagawa
  • Journal Title: Phys. Rev. B 79212301 Pages: 1-4
  • Peer Reviewed
• [Journal Article] Off-center guest vibrations and their effect on lattice thermal conductivity in n-and p-type β-Ba8Ga16Sn30 (2009)
  • Author(s): K. Suekuni, T. Tanaka, S. Yamamoto, M.A. Avila, K. Umeo, Y. Takasu, T. Hasegawa, N. Ogita, M. Udagawa, T. Takabatake
  • Journal Title: Journal of Electronic Materials Vol.38,No.7 Pages: 1516-1520
  • Peer Reviewed
• [Journal Article] Simultaneous structure and carrier tuning of dimorphic clathrate Ba8Ga16Sn30 (2008)
  • Author(s): K. Suekuni, M.A. Avila, K. Umeo, H. Fukuoka, S. Yamanaka, T. Nakagawa, T. Takabatake
  • Journal Title: Phys. Rev. B 77235119 Pages: 1-8
  • Peer Reviewed
• [Journal Article] Off-center rattling and anisotropic expansion of type-I clathrates studied by Raman scattering (2008)
  • Author(s): Y. Takasu, T. Hasegawa, N. Ogita, M. Udagawa, M.A. Avila, K. Suekuni, T. Takabatake
  • Journal Title: Phys. Rev. Lett 100165503 Pages: 1-4
  • Peer Reviewed
• [Journal Article] Ba8Ga16Sn30 with type-I clathrate structure: Drastic suppression of heat conduction (2008)
  • Author(s): M.A. Avila, K. Suekuni, K. Umeo, H. Fukuoka, S. Yamanaka, T. Takabatake
  • Journal Title: Appl. Phys. Lett 92041902 Pages: 1-3
  • Peer Reviewed
• [Journal Article] Cage-size control of guest vibration and thermal conductivity in Sr8Ga16Si30-xGex (2007)
  • Author(s): K. Suekuni, M.A. Avila, K. Umeo, T. Takabatake
  • Journal Title: Phys. Rev. B 75195210 Pages: 1-6
  • Peer Reviewed
• [Journal Article] Elastic properties of Eu8Ga16Ge30 (2007)
  • Author(s): I. Ishii, H. Higaki, S. Morita, M.A. Avila, T. Takabatake, T. Suzuki
  • Journal Title: J. Magn. Magn. Mater 310 Pages: 957-959
  • Peer Reviewed
• [Journal Article] Dynamical properties of guest ions in the type-I clathrate compounds X8Ga16Ge30 (X=Eu, Sr, Ba) investigated by Raman scattering (2006)
  • Author(s): Y. Takasu, T. Hasegawa, N. Ogita, M. Udagawa, M.A. Avila, K. Suekuni, I. Ishii, T. Suzuki, T. Takabatake
  • Journal Title: Phys. Rev. B 74174303 Pages: 1-5
  • Peer Reviewed
• [Journal Article] Glasslike versus crystalline thermal conductivity in carrier-tuned Ba8Ga16X30 clathrates (X=Ge, Sn) (2006)
  • Author(s): M.A. Avila, K. Suekuni, K. Umeo, H. Fukuoka, S. Yamanaka, T. Takabatake
  • Journal Title: Phys. Rev. B 74125109 Pages: 1-8
  • Peer Reviewed
• [Presentation] Thermoelectric clathrates with off-center rattling ions (2009)
  • Author(s): 高畠敏郎
  • Organizer: Croatian- Japanese Workshop on Materials Science
  • Place of Presentation: Zagreb, Croatia(Invited)
  • Year and Date: 2009-06-30
• [Presentation] Local phonon dynamics in thermoelectric clathrates with off- center rattling ions (2008)
  • Author(s): 高畠敏郎
  • Organizer: 10th German- Japanese Symp
  • Place of Presentation: Germany(Oral)
  • Year and Date: 2008-09-30
• [Presentation] Thermoelectrics of Kondo semiconductors and intermetallic clathrates (2008)
  • Author(s): 高畠敏郎
  • Organizer: ARW Workshop on Properties and Applications of Thermoelectric Materials
  • Place of Presentation: Hvar, Croatia(Invited)
  • Year and Date: 2008-09-20
• [Presentation] Thermoelectric properties of f-electron compounds with hybridization gaps (2008)
  • Author(s): 高畠敏郎
  • Organizer: 25th Rare Earth Research Conf
  • Place of Presentation: Tuscaloosa, Alabama, USA(Invited)
  • Year and Date: 2008-06-23
• [Presentation] Thermal conductivity reduction by rattling of nonmagnetic guest ions in skutterudites AT4Sb12 (A=Ca, Sr, Ba, La; T=Fe, Ru, Os) and intermetallic clathrates A8Ga16X30 (A=Sr, Ba; X=Si, Ge, Sn) (2007)
  • Author(s): 高畠敏郎
  • Organizer: Intern. Conf. on New Quantum Phenomena in Skutterudite and Related Systems
  • Place of Presentation: Kobe, Japan(Oral)
  • Year and Date: 2007-09-27
• [Presentation] Thermoelectricity in carrier- controlled clathrates A8Ga16X30 (A=Sr, Ba; X =Ge, Sn) (2006)
  • Author(s): 高畠敏郎
  • Organizer: 25th Intern. Conf. on Thermoelectrics
  • Place of Presentation: Vienna, Austria(Invited)
  • Year and Date: 2006-08-08
• [Book] 熱電変換技術ハンドブック,第2章熱電変換材料,希土類近藤半導体(監修梶川武信) (2008)
  • Author(s): 高畠敏郎
  • Total Pages: 170-175
  • Publisher: NTS出版
• [Book] 土類の機能と応用,第5章エレクトロニクス機能分野への応用4. 熱電変換材料(監修:足立吟也) (2006)
  • Author(s): 北川二郎,高畠敏郎
  • Total Pages: 205-211
  • Publisher: シーエムシー出版
• [Book] 熱電変換システムの高効率化・高信頼性化技術第1章第4節充填スクッテルダイト (2006)
  • Author(s): 高畠敏郎
  • Total Pages: 62-73
  • Publisher: 技術情報協会
• [Remarks] 鬼丸孝博,高畠敏郎「カゴ構造と異種電子系が作り出す強相関現象希土類内包カゴ物質育成」科学新聞2010年3月26日
• [Remarks] 豊田直樹,高畠敏郎,宇田川眞行「原子のラットリング振動テラヘルツ光撮影に成功」科学新聞2009年7月17日
• [Remarks] 宇田川眞行,高畠敏郎「熱伝導率の原因解明」毎日新聞2008年5月20日朝刊6頁
• [Remarks] 宇田川眞行,高畠敏郎「熱伝導制御原子の動き解明」科学新聞2008年6月6日
• [Remarks] 宇田川眞行,高畠敏郎「夢の熱電物質開発へ」中国新聞2008年5月31日朝刊1頁賞 (1)宇田川眞行,高畠敏郎第7回広島大学学長表彰,2008年11月26日「熱電変換クラスレートの熱伝導率抑制の機構を解明」