Evaluation of the thermoelectric potential of the type-I clathrate Ba8NiyZnxGe46−x−y

A detailed investigation of the high-temperature thermoelectric properties of the ternary clathrate of type-I Ba8ZnxGe46−x for the range 7.2 x 7.8 is presented. Electrical resistivity, Seebeck coefficient, thermal conductivity and Hall-effect measurements clearly demonstrate that the maximum ZT-valu...

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Bibliographic Details
Published in:Journal of physics. D, Applied physics Applied physics, 2012-05, Vol.45 (21)
Main Authors: Falmbigl, M, Nasir, N, Grytsiv, A, Rogl, P, Seichter, S, Zavarsky, A, Royanian, E, Bauer, E
Format: Article
Language:English
Subjects:
clathrate
thermoelectric properties
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Summary:A detailed investigation of the high-temperature thermoelectric properties of the ternary clathrate of type-I Ba8ZnxGe46−x for the range 7.2 x 7.8 is presented. Electrical resistivity, Seebeck coefficient, thermal conductivity and Hall-effect measurements clearly demonstrate that the maximum ZT-value can be expected for the composition Ba8Zn7.7Ge38.3, which reaches ZT ∼ 0.46 at a temperature of 730 K. Furthermore, the influence on the thermoelectric properties was studied for partial substitution of Zn by one Ni-atom (Ba8NiyZnxGe46−x−y with ynom = 1, and 6.5 x 7.2) or by three Ni-atoms per unit cell (Ba8NiyZnxGe46−x−y with ynom = 3 and x = 1 to 3). Whereas a small amount of Ni increases the figure of merit ZT to 0.65 at 800 K, a higher Ni-content reduces the thermoelectric performance. Hall-effect measurements reveal that this improvement is essentially due to an increased charge carrier mobility.
ISSN:0022-3727
1361-6463
DOI:10.1088/0022-3727/45/21/215308