Structural analysis and thermoelectric properties of Type-I clathrate compounds in the Ba-Ge-Ga system

Norihiko L. Okamoto, Takunii Nishii, Min Wook Oh, Haruyuki Inui

Research output: Contribution to journalConference article

3 Citations (Scopus)

Abstract

The crystal structure and thermoelectric properties of Type-I clathrate compounds in the Ba-Ge-Ga system (Ba8GaxGe46-x) have been investigated as a function of Ga content. While all ternary compounds containing more than 3 Ga exhibit a crystal structure of normal Type-I clathrates with the space group Pm3n, the binary compound possesses a composition Ba8Ge43, which is leaner in Ge than the stoichiometric composition, and has a crystal structure different from that of normal Type-I clathrates because of the ordering of Ge vacancies in 6c sites of the parent normal Type-I clathrate structure. The temperature dependence of electrical resistivity of binary Ba8Ge43 is of semiconductor while that for all the ternary compounds is metallic. The value of Seebeck coefficient increases with the increase in the Ga content. The value of dimensionless figure of merit (ZT) increases with the increase in the Ga content, exhibiting a high value of 0.76 at 700°C for Ba8Ga 16Ge30.

Original languageEnglish
Pages (from-to)187-192
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume793
Publication statusPublished - 2003 Dec 1
Externally publishedYes
EventThermoelectric Materials 2003 - Research and Applications - Boston, MA., United States
Duration: 2003 Dec 12003 Dec 3

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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