Recent experimental work on lanthanum telluride has confirmed its significant potential as an n‐type material for high temperature thermoelectric (TE) power generation application. The phase of interest, La 3− x Te 4 , has a Th 3 P 4 defect structure where x is the lanthanum vacancy with values ranging between 0 and 1/3. Thermoelectric properties change rapidly with x since the carrier concentration, n, is proportional to the (1−3x) parameter. Controlling the Te to La stoichiometry in lanthanum telluride is thus vital to achieving the optimum self‐doping level for the highest dimensionless figure of merit ZT value. We report on a significant improvement in reproducibly preparing this refractory compound over prior lengthy and unwieldy high temperature experimental techniques developed in the 1980's. Mechanochemical processes are utilized to synthesize precise stoichiometries of lanthanum telluride at room temperature, enabling improved characterization, analysis and modeling of its transport properties as a function of the number of La vacancies. We report TE properties for a large range of the allowed compositions, with ZT values greater than 1.0 obtained at 1275 K for several compositions. In addition to stoichiometric optimization within the pure compound, chemical substitutions can enhance performance by decreasing the lattice thermal conductivity and tuning the electrical properties for maximum ZT values at lower temperatures; preliminary studies indicate that the addition of ytterbium increases ZT. Some properties pertaining to device development are discussed. Specifically, lanthanum telluride has a low sublimation rate, and a coefficient of thermal expansion that closely matches a p‐type rare earth compound analog (the Yb 14 MnSb 11 Zintl compound).


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    Titel :

    Lanthanum Telluride: Mechanochemical Synthesis of a Refractory Thermoelectric Material


    Beteiligte:
    May, Andrew (Autor:in) / Snyder, Jeff (Autor:in) / Fleurial, Jean‐Pierre (Autor:in) / El‐Genk, Mohamed S. (Herausgeber:in)

    Kongress:

    SPACE TECHNOLOGY AND APPLICATIONS INTERNATIONAL FORUM‐STAIF 2008: 12th Conference on Thermophysics Applications in Microgravity; 1st Symposium on Space Resource Utilization; 25th Symposium on Space Nuclear Power and Propulsion; 6th Conference on Human/Robotic Technology and the Vision for Space Exploration; 6th Symposium on Space Colonization; 5th Symposium on New Frontiers and Future Concept ; 2008 ; Albuquerque (New Mexico)


    Erschienen in:

    AIP Conference Proceedings ; 969 , 1 ; 672-678


    Erscheinungsdatum :

    21.01.2008


    Format / Umfang :

    7 pages





    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch




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