Comparison for thermoelectric properties of BiTe based semiconductor processed by the mechanical alloying and the high pressure torsion after melt grown by the vertical Bridgman method

Kazuhiro Hasezaki, Maki Ashida, Takashi Hamachiyo, Hirotaka Matsunoshita, Zenji Horita

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Bi2Te3-related thermoelectric semiconductors were prepared by the mechanical alloying (MA) and the vertical Bridgman (VBM) - High Pressure Torsion (HPT) methods. Structures and electric properties of these alloys were then investigated. These samples had a nominal composition of Bi0.5Sb1.5Te3.0 with 0.07 mass% excess Te. The MA sample was sintered into a compact after mechanical alloying by hot-pressing while the VBM - HPT sample was subjected by HPT after being cut into a disk from a melt-grown ingot by the vertical Bridgman method (VBM). The orientation factors of the MA and VBM - HPT samples were 0.054 and 0.525, respectively, indicating that the preferred orientation was formed by VBM - HPT. Average grain sizes of both samples were approximately 2 μm. By estimating the slope of carrier mobility versus temperature the carrier scattering factor of the MA and VBM - HPT samples were estimated to be -2.8 and -1.4. These values are indicative of carrier scatterings by acoustic phonons and by the interaction between acoustic and optical phonons, respectively. The maximum power factor obtained for the isotropic MA sample was 4.1 × 10-3W m -1 K-2 at 310 K and this was about twice the 2.1 × 10-3W m-1 K-2 at 440K obtained for the anisotropic VBM - HPT sample.

    Original languageEnglish
    Title of host publicationTHERMEC 2009
    EditorsTara Chandra, Tara Chandra, Tara Chandra, N. Wanderka, N. Wanderka, N. Wanderka, Walter Reimers, Walter Reimers, Walter Reimers, M. Ionescu, M. Ionescu, M. Ionescu
    PublisherTrans Tech Publications Ltd
    Pages1923-1928
    Number of pages6
    ISBN (Print)0878492941, 9780878492947
    DOIs
    Publication statusPublished - 2010
    Event6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2009 - Berlin, Germany
    Duration: Aug 25 2009Aug 29 2009

    Publication series

    NameMaterials Science Forum
    Volume638-642
    ISSN (Print)0255-5476
    ISSN (Electronic)1662-9752

    Other

    Other6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2009
    Country/TerritoryGermany
    CityBerlin
    Period8/25/098/29/09

    All Science Journal Classification (ASJC) codes

    • General Materials Science
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering

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