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High temperature thermoelectric properties of the type-I clathrate Ba_8Ni_xGe_(46−x−y□y)

Aydemir, U. and Candolfi, C. and Ormeci, A. and Baitinger, M. and Oeschler, N. and Steglich, F. and Grin, Yu (2014) High temperature thermoelectric properties of the type-I clathrate Ba_8Ni_xGe_(46−x−y□y). Journal of Physics: Condensed Matter, 26 (48). Art. No. 485801. ISSN 0953-8984. doi:10.1088/0953-8984/26/48/485801.

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Polycrystalline samples of the type-I clathrate Ba_8Ni_xGe_(46−x−y□y) were synthesized for 0.2 ≤ x ≤ 3.5 by melt quenching and for 3.5<x ≤ 6.0 by melting with subsequent annealing at 700 °C. The maximum Ni content in the clathrate framework at this temperature was found to be x ≈ 4.2 atoms per unit cell. Thermoelectric and thermodynamic properties of the type-I clathrate were investigated from 300 to 700 K by means of electrical resistivity, thermopower, thermal conductivity and specific heat measurements. As the Ni content increases, the electronic properties gradually evolve from a metallic character (x < 3.5) towards a highly doped semiconducting state (x ≥ 3.5). Below x ≈ 4.0 transport is dominated by electrons, while further addition of Ni (x ≈ 4.2) switches the electrical conduction to p-type. Maximum value of the dimensionless thermoelectric figure of merit ZT ≈ 0.2 was achieved at 500 K and 650 K for x ≈ 2.0 and x ≈ 3.8, respectively.

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Aydemir, U.0000-0003-1164-1973
Additional Information:© 2014 IOP Publishing Ltd. Received 12 August 2014, revised 30 September 2014. Accepted for publication 13 October 2014. Published 6 November 2014. The authors thank Petra Scheppan, Renate Hempel-Weber and members of the Kompetenzgruppe Struktur for providing experimental support. CC acknowledges the financial support of the CNRS-MPG program. YuG gratefully acknowledges financial support by the Deutsche Forschungsgemeinschaft (SPP 1386).
Funding AgencyGrant Number
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)SPP 1386
Subject Keywords:clathrate, thermoelectric, thermal conductivity
Issue or Number:48
Classification Code:PACS: 72.15.Jf, 81.40.Ef, 65.40.Ba, 65.40.G-
Record Number:CaltechAUTHORS:20150106-135219256
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Official Citation:High temperature thermoelectric properties of the type-I clathrate Ba8NixGe46−x−y□y U Aydemir et al 2014 J. Phys.: Condens. Matter 26 485801
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53219
Deposited By: Ruth Sustaita
Deposited On:09 Jan 2015 16:44
Last Modified:10 Nov 2021 19:49

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